mirror of
https://github.com/Xahau/xahaud.git
synced 2025-12-06 17:27:52 +00:00
Update soci
This commit is contained in:
Brad Chase
313
src/soci/docs/api/backend.md
Normal file
313
src/soci/docs/api/backend.md
Normal file
@@ -0,0 +1,313 @@
|
||||
# Backends reference
|
||||
|
||||
This part of the documentation is provided for those who want towrite (and contribute!) their
|
||||
own backends. It is anyway recommendedthat authors of new backend see the code of some existing
|
||||
backend forhints on how things are really done.
|
||||
|
||||
The backend interface is a set of base classes that the actual backendsare supposed to specialize.
|
||||
The main SOCI interface uses only theinterface and respecting the protocol (for example,
|
||||
the order of function calls) described here.
|
||||
Note that both the interface and theprotocol were initially designed with the Oracle database in
|
||||
mind, which means that whereas it is quite natural with respect to the way Oracle API (OCI) works,
|
||||
it might impose some implementation burden on otherbackends, where things are done differently
|
||||
and therefore have to beadjusted, cached, converted, etc.
|
||||
|
||||
The interface to the common SOCI interface is defined in the `core/soci-backend.h` header file.
|
||||
This file is dissected below.
|
||||
|
||||
All names are defined in either `soci` or `soci::details` namespace.
|
||||
|
||||
```cpp
|
||||
// data types, as seen by the user
|
||||
enum data_type
|
||||
{
|
||||
dt_string, dt_date, dt_double, dt_integer, dt_long_long, dt_unsigned_long_long
|
||||
};
|
||||
|
||||
// the enum type for indicator variables
|
||||
enum indicator { i_ok, i_null, i_truncated };
|
||||
|
||||
// data types, as used to describe exchange format
|
||||
enum exchange_type
|
||||
{
|
||||
x_char,
|
||||
x_stdstring,
|
||||
x_short,
|
||||
x_integer,
|
||||
x_long_long,
|
||||
x_unsigned_long_long,
|
||||
x_double,
|
||||
x_stdtm,
|
||||
x_statement,
|
||||
x_rowid,
|
||||
x_blob
|
||||
};
|
||||
|
||||
struct cstring_descriptor
|
||||
{
|
||||
cstring_descriptor(char * str, std::size_t bufSize)
|
||||
: str_(str), bufSize_(bufSize) {}
|
||||
|
||||
char * str_;
|
||||
std::size_t bufSize_;
|
||||
};
|
||||
|
||||
// actually in error.h:
|
||||
class soci_error : public std::runtime_error
|
||||
{
|
||||
public:
|
||||
soci_error(std::string const & msg);
|
||||
};
|
||||
```
|
||||
|
||||
The `data_type` enumeration type defines all types that form the core type support for SOCI.
|
||||
The enum itself can be used by clients when dealing with dynamic rowset description.
|
||||
|
||||
The `indicator` enumeration type defines all recognized *states* of data.
|
||||
The `i_truncated` state is provided for the case where the string is retrieved from the database
|
||||
into the char buffer that is not long enough to hold the whole value.
|
||||
|
||||
The `exchange_type` enumeration type defines all possible types that can be used
|
||||
with the `into` and `use` elements.
|
||||
|
||||
The `cstring_descriptor` is a helper class that allows to store the address of `char` buffer
|
||||
together with its size.
|
||||
The objects of this class are passed to the backend when the `x_cstring` type is involved.
|
||||
|
||||
The `soci_error` class is an exception type used for database-related (and also usage-related) errors.
|
||||
The backends should throw exceptions of this or derived type only.
|
||||
|
||||
```cpp
|
||||
class standard_into_type_backend
|
||||
{
|
||||
public:
|
||||
standard_into_type_backend() {}
|
||||
virtual ~standard_into_type_backend() {}
|
||||
|
||||
virtual void define_by_pos(int& position, void* data, exchange_type type) = 0;
|
||||
|
||||
virtual void pre_fetch() = 0;
|
||||
virtual void post_fetch(bool gotData, bool calledFromFetch, indicator* ind) = 0;
|
||||
|
||||
virtual void clean_up() = 0;
|
||||
};
|
||||
```
|
||||
|
||||
The `standard_into_type_back_end` class implements the dynamic interactions with the simple
|
||||
(non-bulk) `into` elements.
|
||||
The objects of this class (or, rather, of the derived class implemented by the actual backend)
|
||||
are created by the `statement` object when the `into` element is bound - in terms of lifetime
|
||||
management, `statement` is the master of this class.
|
||||
|
||||
* `define_by_pos` - Called when the `into` element is bound, once and before the statement is executed. The `data` pointer points to the variable used for `into` element (or to the `cstring_descriptor` object, which is artificially created when the plain `char` buffer is used for data exchange). The `position` parameter is a "column number", assigned by the library. The backend should increase this parameter, according to the number of fields actually taken (usually 1).
|
||||
* `pre_fetch` - Called before each row is fetched.
|
||||
* `post_fetch` - Called after each row is fetched. The `gotData` parameter is `true` if the fetch operation really retrievedsome data and `false` otherwise; `calledFromFetch` is `true` when the call is from the fetch operation and `false` if it is from the execute operation (this is also the case for simple, one-time queries). In particular, `(calledFromFetch && !gotData)` indicates that there is an end-of-rowset condition. `ind` points to the indicator provided by the user, or is `NULL`, if there is no indicator.
|
||||
* `clean_up` - Called once when the statement is destroyed.
|
||||
|
||||
The intended use of `pre_fetch` and `post_fetch` functions is to manage any internal buffer and/or data conversion foreach value retrieved from the database.
|
||||
If the given server supportsbinary data transmission and the data format for the given type agreeswith what is used on the client machine, then these two functions neednot do anything; otherwise buffer management and data conversionsshould go there.
|
||||
|
||||
```cpp
|
||||
class vector_into_type_backend
|
||||
{
|
||||
public:
|
||||
vector_into_type_backend() {}
|
||||
virtual ~vector_into_type_backend() {}
|
||||
|
||||
virtual void define_by_pos(int& position, void* data, exchange_type type) = 0;
|
||||
|
||||
virtual void pre_fetch() = 0;
|
||||
virtual void post_fetch(bool gotData, indicator* ind) = 0;
|
||||
|
||||
virtual void resize(std::size_t sz) = 0;
|
||||
virtual std::size_t size() = 0;
|
||||
|
||||
virtual void clean_up() = 0;
|
||||
};
|
||||
```
|
||||
|
||||
The `vector_into_type_back_end` has similar structure and purpose as the previous one, but is used for vectors (bulk data retrieval).
|
||||
|
||||
The `data` pointer points to the variable of type `std::vector<T>;` (and *not* to its internal buffer), `resize` is supposed to really resize the user-provided vector and `size` is supposed to return the current size of this vector.
|
||||
The important difference with regard to the previous class is that `ind` points (if not `NULL`) to the beginning of the *array* of indicators.
|
||||
The backend should fill this array according to the actual state of the retrieved data.
|
||||
|
||||
* `bind_by_pos` - Called for each `use` element, once and before the statement is executed - for those `use` elements that do not provide explicit names for parameter binding. The meaning of parameters is same as in previous classes.
|
||||
* `bind_by_name` - Called for those `use` elements that provide the explicit name.
|
||||
* `pre_use` - Called before the data is transmitted to the server (this means before the statement is executed, which can happen many times for the prepared statement). `ind` points to the indicator provided by the user (or is `NULL`).
|
||||
* `post_use` - Called after statement execution. `gotData` and `ind` have the same meaning as in `standard_into_type_back_end::post_fetch`, and this can be used by those backends whose respective servers support two-way data exchange (like in/out parameters in stored procedures).
|
||||
|
||||
The intended use for `pre_use` and `post_use` methods is to manage any internal buffers and/or data conversion.
|
||||
They can be called many times with the same statement.
|
||||
|
||||
```cpp
|
||||
class vector_use_type_backend
|
||||
{
|
||||
public:
|
||||
virtual ~vector_use_type_backend() {}
|
||||
|
||||
virtual void bind_by_pos(int& position,
|
||||
void* data, exchange_type type) = 0;
|
||||
virtual void bind_by_name(std::string const& name,
|
||||
void* data, exchange_type type) = 0;
|
||||
|
||||
virtual void pre_use(indicator const* ind) = 0;
|
||||
|
||||
virtual std::size_t size() = 0;
|
||||
|
||||
virtual void clean_up() = 0;
|
||||
};
|
||||
```
|
||||
|
||||
Objects of this type (or rather of type derived from this one) are used to implement interactions with user-provided vector (bulk) `use` elements and are managed by the `statement` object.
|
||||
The `data` pointer points to the whole vector object provided by the user (and *not* to its internal buffer); `ind` points to the beginning of the array of indicators (or is `NULL`).
|
||||
The meaning of this interface is analogous to those presented above.
|
||||
|
||||
```cpp
|
||||
class statement_backend
|
||||
{
|
||||
public:
|
||||
statement_backend() {}
|
||||
virtual ~statement_backend() {}
|
||||
|
||||
virtual void alloc() = 0;
|
||||
virtual void clean_up() = 0;
|
||||
|
||||
virtual void prepare(std::string const& query, statement_type eType) = 0;
|
||||
|
||||
enum exec_fetch_result
|
||||
{
|
||||
ef_success,
|
||||
ef_no_data
|
||||
};
|
||||
|
||||
virtual exec_fetch_result execute(int number) = 0;
|
||||
virtual exec_fetch_result fetch(int number) = 0;
|
||||
|
||||
virtual long long get_affected_rows() = 0;
|
||||
virtual int get_number_of_rows() = 0;
|
||||
|
||||
virtual std::string rewrite_for_procedure_call(std::string const& query) = 0;
|
||||
|
||||
virtual int prepare_for_describe() = 0;
|
||||
virtual void describe_column(int colNum, data_type& dtype,
|
||||
std::string& column_name) = 0;
|
||||
|
||||
virtual standard_into_type_backend* make_into_type_backend() = 0;
|
||||
virtual standard_use_type_backend* make_use_type_backend() = 0;
|
||||
virtual vector_into_type_backend* make_vector_into_type_backend() = 0;
|
||||
virtual vector_use_type_backend* make_vector_use_type_backend() = 0;
|
||||
};
|
||||
```
|
||||
|
||||
The `statement_backend` type implements the internals of the `statement` objects.
|
||||
The objects of this class are created by the `session` object.
|
||||
|
||||
* `alloc` - Called once to allocate everything that is needed for the statement to work correctly.
|
||||
* `clean_up` - Supposed to clean up the resources, called once.
|
||||
* `prepare` - Called once with the text of the SQL query. For servers that support explicit query preparation, this is the place to do it.
|
||||
* `execute` - Called to execute the query; if number is zero, the intent is not to exchange data with the user-provided objects (`into` and `use` elements); positive values mean the number of rows to exchange (more than 1 is used only for bulk operations).
|
||||
* `fetch` - Called to fetch next bunch of rows; number is positive and determines the requested number of rows (more than 1 is used only for bulk operations).
|
||||
* `get_affected_rows` - Called to determine the actual number of rows affected by data modifying statement.
|
||||
* `get_number_of_rows` - Called to determine the actual number of rows retrieved by the previous call to `execute` or `fetch`.
|
||||
* `rewrite_for_procedure_call` - Used when the `procedure` is used instead of `statement`, to call the stored procedure. This function should rewrite the SQL query (if necessary) to the form that will allow to execute the given procedure.
|
||||
* `prepare_for_describe` - Called once when the `into` element is used with the `row` type, which means that dynamic rowset description should be performed. It is supposed to do whatever is needed to later describe the column properties and should return the number of columns.
|
||||
* `describe_column` - Called once for each column (column numbers - `colNum` - start from 1), should fill its parameters according to the column properties.
|
||||
* `make_into_type_backend`, `make_use_type_backend`, `make_vector_into_type_backend`, `make_vector_use_type_backend` - Called once for each `into` or `use` element, to create the objects of appropriate classes (described above).
|
||||
|
||||
**Notes:**
|
||||
|
||||
1. Whether the query is executed using the simple one-time syntax or is prepared, the `alloc`, `prepare` and `execute` functions are always called, in this order.
|
||||
2. All `into` and `use` elements are bound (their `define_by_pos` or `bind_by_pos`/`bind_by_name` functions are called) *between* statement preparation and execution.
|
||||
|
||||
```cpp
|
||||
class rowid_backend
|
||||
{
|
||||
public:
|
||||
virtual ~rowid_backend() {}
|
||||
};
|
||||
```
|
||||
|
||||
The `rowid_backend` class is a hook for the backends to provide their own state for the row identifier. It has no functions, since the only portable interaction with the row identifier object is to use it with `into` and `use` elements.
|
||||
|
||||
```cpp
|
||||
class blob_backend
|
||||
{
|
||||
public:
|
||||
virtual ~blob_backend() {}
|
||||
|
||||
virtual std::size_t get_len() = 0;
|
||||
virtual std::size_t read(std::size_t offset, char * buf,
|
||||
std::size_t toRead) = 0;
|
||||
virtual std::size_t write(std::size_t offset, char const * buf,
|
||||
std::size_t toWrite) = 0;
|
||||
virtual std::size_t append(char const * buf, std::size_t toWrite) = 0;
|
||||
virtual void trim(std::size_t newLen) = 0;
|
||||
};
|
||||
```
|
||||
|
||||
The `blob_backend` interface provides the entry points for the `blob` methods.
|
||||
|
||||
```cpp
|
||||
class session_backend
|
||||
{
|
||||
public:
|
||||
virtual ~session_backend() {}
|
||||
|
||||
virtual void begin() = 0;
|
||||
virtual void commit() = 0;
|
||||
virtual void rollback() = 0;
|
||||
|
||||
virtual bool get_next_sequence_value(session&, std::string const&, long&);
|
||||
virtual bool get_last_insert_id(session&, std::string const&, long&);
|
||||
|
||||
virtual std::string get_backend_name() const = 0;
|
||||
|
||||
virtual statement_backend * make_statement_backend() = 0;
|
||||
virtual rowid_backend * make_rowid_backend() = 0;
|
||||
virtual blob_backend * make_blob_backend() = 0;
|
||||
};
|
||||
```
|
||||
|
||||
The object of the class derived from `session_backend` implements the internals of the `session` object.
|
||||
|
||||
* `begin`, `commit`, `rollback` - Forward-called when the same functions of `session` are called by user.
|
||||
* `get_next_sequence_value`, `get_last_insert_id` - Called to retrieve sequences or auto-generated values and every backend should define at least one of them to allow the code using auto-generated values to work.
|
||||
* `make_statement_backend`, `make_rowid_backend`, `make_blob_backend` - Called to create respective implementations for the `statement`, `rowid` and `blob` classes.
|
||||
|
||||
```cpp
|
||||
struct backend_factory
|
||||
{
|
||||
virtual ~backend_factory() {}
|
||||
|
||||
virtual details::session_backend * make_session(
|
||||
std::string const& connectString) const = 0;
|
||||
};
|
||||
```
|
||||
|
||||
The `backend_factory` is a base class for backend-provided factory class that is able to create valid sessions. The `connectString` parameter passed to `make_session` is provided here by the `session` constructor and contains only the backend-related parameters, without the backend name (if the dynamic backend loading is used).
|
||||
|
||||
The actual backend factory object is supposed to be provided by the backend implementation and declared in its header file. In addition to this, the `factory_ABC` function with the "C" calling convention and returning the pointer to concrete factory object should be provided, where `ABC` is the backend name.
|
||||
|
||||
The following example is taken from `soci-postgresql.h`, which declares entities of the PostgreSQL backend:
|
||||
|
||||
```cpp
|
||||
struct postgresql_backend_factory : backend_factory
|
||||
{
|
||||
virtual postgresql_session_backend* make_session(
|
||||
std::string const& connectString) const;
|
||||
};
|
||||
extern postgresql_backend_factory const postgresql;
|
||||
|
||||
extern "C"
|
||||
{
|
||||
|
||||
// for dynamic backend loading
|
||||
backend_factory const * factory_postgresql();
|
||||
|
||||
} // extern "C"
|
||||
```
|
||||
|
||||
With the above declarations, it is enough to pass the `postgresql` factory name to the constructor of the `session` object, which will use this factory to create concrete implementations for any other objects that are needed, with the help of appropriate `make_XYZ` functions. Alternatively, the `factory_postgresql` function will be called automatically by the backend loader if the backend name is provided at run-time instead.
|
||||
|
||||
Note that the backend source code is placed in the `backends/*name*` directory (for example, `backends/oracle`) and the test driver is in `backends/*name*/test`. There is also `backends/empty` directory provided as a skeleton for development of new backends and their tests. It is recommended that all backends respect naming conventions by just appending their name to the base-class names. The backend name used for the global factory object should clearly identify the given database engine, like `oracle`, `postgresql`, `mysql`, and so on.
|
||||
753
src/soci/docs/api/client.md
Normal file
753
src/soci/docs/api/client.md
Normal file
@@ -0,0 +1,753 @@
|
||||
# API Reference
|
||||
|
||||
The core client interface is a set of classes and free functions declared in the `soci.h` header file.
|
||||
All names are dbeclared in the `soci` namespace.
|
||||
|
||||
There are also additional names declared in the `soci::details` namespace, but they are not supposed to be directly used by the users of the library and are therefore not documented here.
|
||||
When such types are used in the declarations that are part of the "public" interface, they are replaced by "IT", which means "internal type".
|
||||
Types related to the backend interface are named here.
|
||||
|
||||
## Commonly used types
|
||||
|
||||
The following types are commonly used in the rest of the interface:
|
||||
|
||||
```cpp
|
||||
// data types, as seen by the user
|
||||
enum data_type { dt_string, dt_date, dt_double, dt_integer, dt_long_long, dt_unsigned_long_long };
|
||||
|
||||
// the enum type for indicator variables
|
||||
enum indicator { i_ok, i_null, i_truncated };
|
||||
|
||||
// the type used for reporting exceptions
|
||||
class soci_error : public std::runtime_error { /* ... */ };
|
||||
```
|
||||
|
||||
The `data_type` type defines the basic SOCI data types. User provided data types need to be associated with one of these basic types.
|
||||
|
||||
The `indicator` type defines the possible states of data.
|
||||
|
||||
The `soci_error` type is used for error reporting.
|
||||
|
||||
## class session
|
||||
|
||||
The `session` class encapsulates the connection to the database.
|
||||
|
||||
```cpp
|
||||
class session
|
||||
{
|
||||
public:
|
||||
session();
|
||||
explicit session(connection_parameters const & parameters);
|
||||
session(backend_factory const & factory, std::string const & connectString);
|
||||
session(std::string const & backendName, std::string const & connectString);
|
||||
explicit session(std::string const & connectString);
|
||||
explicit session(connection_pool & pool);
|
||||
|
||||
~session();
|
||||
|
||||
void open(backend_factory const & factory, std::string const & connectString);
|
||||
void open(std::string const & backendName, std::string const & connectString);
|
||||
void open(std::string const & connectString);
|
||||
void close();
|
||||
void reconnect();
|
||||
|
||||
void begin();
|
||||
void commit();
|
||||
void rollback();
|
||||
|
||||
*IT* once;
|
||||
*IT* prepare;
|
||||
|
||||
template <typename T> *IT* operator<<(T const & t);
|
||||
|
||||
bool got_data() const;
|
||||
|
||||
bool get_next_sequence_value(std::string const & sequence, long & value);
|
||||
bool get_last_insert_id(std::string const & table, long & value);
|
||||
|
||||
std::ostringstream & get_query_stream();
|
||||
|
||||
void set_log_stream(std::ostream * s);
|
||||
std::ostream * get_log_stream() const;
|
||||
|
||||
std::string get_last_query() const;
|
||||
|
||||
void uppercase_column_names(bool forceToUpper);
|
||||
|
||||
std::string get_dummy_from_table() const;
|
||||
std::string get_dummy_from_clause() const;
|
||||
|
||||
details::session_backend * get_backend();
|
||||
|
||||
std::string get_backend_name() const;
|
||||
};
|
||||
```
|
||||
|
||||
This class contains the following members:
|
||||
|
||||
* Various constructors. The default one creates the session in the disconnected state. The others expect the backend factory object, or the backend name, or the URL-like composed connection string or the special parameters object containing both the backend and the connection string as well as possibly other connection options. The last constructor creates a session proxy associated with the session that is available in the given pool and releases it back to the pool when its lifetime ends. Example:
|
||||
|
||||
```cpp
|
||||
session sql(postgresql, "dbname=mydb");
|
||||
session sql("postgresql", "dbname=mydb");
|
||||
session sql("postgresql://dbname=mydb");
|
||||
```
|
||||
|
||||
* The constructors that take backend name as string load the shared library (if not yet loaded) with name computed as `libsoci_ABC.so` (or `libsoci_ABC.dll` on Windows) where `ABC` is the given backend name.
|
||||
* `open`, `close` and `reconnect` functions for reusing the same session object many times; the `reconnect` function attempts to establish the connection with the same parameters as most recently used with constructor or `open`. The arguments for `open` are treated in the same way as for constructors.
|
||||
* `begin`, `commit` and `rollback` functions for transaction control.
|
||||
* `once` member, which is used for performing *instant* queries that do not need to be separately prepared. Example:
|
||||
|
||||
```cpp
|
||||
sql.once << "drop table persons";
|
||||
```
|
||||
|
||||
* `prepare` member, which is used for statement preparation - the result of the statement preparation must be provided to the constructor of the `statement` class. Example:
|
||||
|
||||
```cpp
|
||||
int i;
|
||||
statement st = (sql.prepare <<
|
||||
"insert into numbers(value) values(:val)", use(i));
|
||||
```
|
||||
|
||||
`operator<<` that is a shortcut forwarder to the equivalent operator of the `once` member. Example:
|
||||
|
||||
```cpp
|
||||
sql << "drop table persons";
|
||||
```
|
||||
|
||||
* `got_data` returns true if the last executed query had non-empty result.
|
||||
* `get_next_sequence_value` returns true if the next value of the sequence with the specified name was generated and returned in its second argument. Unless you can be sure that your program will use only databases that support sequences, consider using this method in conjunction with `get_last_insert_id()` as explained in ["Working with sequences"](beyond.html#sequences) section.
|
||||
* `get_last_insert_id` returns true if it could retrieve the last value automatically generated by the database for an auto-incremented field. Notice that although this method takes the table name, for some databases, such as Microsoft SQL Server and SQLite, this value is actually global, so you should attempt to retrieve it immediately after performing an insertion.
|
||||
* `get_query_stream` provides direct access to the stream object that is used to accumulate the query text and exists in particular to allow the user to imbue specific locale to this stream.
|
||||
* `set_log_stream` and `get_log_stream` functions for setting and getting the current stream object used for basic query logging. By default, it is `NULL`, which means no logging The string value that is actually logged into the stream is one-line verbatim copy of the query string provided by the user, without including any data from the `use` elements. The query is logged exactly once, before the preparation step.
|
||||
* `get_last_query` retrieves the text of the last used query.
|
||||
* `uppercase_column_names` allows to force all column names to uppercase in dynamic row description; this function is particularly useful for portability, since various database servers report column names differently (some preserve case, some change it).
|
||||
* `get_dummy_from_table` and `get_dummy_from_clause()`: helpers for writing portable DML statements, see [DML helpers](statement.html#dml) for more details.
|
||||
* `get_backend` returns the internal pointer to the concrete backend implementation of the session. This is provided for advanced users that need access to the functionality that is not otherwise available.
|
||||
* `get_backend_name` is a convenience forwarder to the same function of the backend object.
|
||||
|
||||
See [Connections and simple queries](basics.html) for more examples.
|
||||
|
||||
## class connection_parameters
|
||||
|
||||
The `connection_parameters` class is a simple container for the backend pointer, connection string and any other connection options. It is used together with `session` constructor and `open()` method.
|
||||
|
||||
```cpp
|
||||
class connection_parameters
|
||||
{
|
||||
public:
|
||||
connection_parameters();
|
||||
connection_parameters(backend_factory const & factory, std::string const & connectString);
|
||||
connection_parameters(std::string const & backendName, std::string const & connectString);
|
||||
explicit connection_parameters(std::string const & fullConnectString);
|
||||
|
||||
void set_option(const char * name, std::string const & value);
|
||||
bool get_option(const char * name, std::string & value) const
|
||||
};
|
||||
```
|
||||
|
||||
The methods of this class are:
|
||||
|
||||
* Default constructor is rarely used as it creates an uninitialized object and the only way to initialize it later is to assign another, valid, connection_parameters object to this one.
|
||||
* The other constructors correspond to the similar constructors of the `session` class and specify both the backend, either as a pointer to it or by name, and the connection string.
|
||||
* `set_option` can be used to set the value of an option with the given name. Currently all option values are strings, so if you need to set a numeric option you need to convert it to a string first. If an option with the given name had been already set before, its old value is overwritten.
|
||||
|
||||
## class connection_pool
|
||||
|
||||
The `connection_pool` class encapsulates the thread-safe pool of connections and ensures that only one thread at a time has access to any connection that it manages.
|
||||
|
||||
```cpp
|
||||
class connection_pool
|
||||
{
|
||||
public:
|
||||
explicit connection_pool(std::size_t size);
|
||||
~connection_pool();
|
||||
|
||||
session & at(std::size_t pos);
|
||||
|
||||
std::size_t lease();
|
||||
bool try_lease(std::size_t & pos, int timeout);
|
||||
void give_back(std::size_t pos);
|
||||
};
|
||||
```
|
||||
|
||||
The operations of the pool are:
|
||||
|
||||
* Constructor that takes the intended size of the pool. After construction, the pool contains regular `session` objects in disconnected state.
|
||||
* `at` function that provides direct access to any given entryin the pool. This function is *non-synchronized*.
|
||||
* `lease` function waits until some entry is available (which means that it is not used) and returns the position of that entry in the pool, marking it as *locked*.
|
||||
* `try_lease` acts like `lease`, but allows to set up a time-out (relative, in milliseconds) on waiting. Negative time-out value means no time-out. Returns `true` if the entry was obtained, in which case its position is written to the `pos` parametr, and `false` if no entry was available before the time-out.
|
||||
* `give_back` should be called when the entry on the given position is no longer in use and can be passed to other requesting thread.
|
||||
|
||||
## class transaction
|
||||
|
||||
The class `transaction` can be used for associating the transaction with some code scope. It is a RAII wrapper for regular transaction operations that automatically rolls back in its destructor *if* the transaction was not explicitly committed before.
|
||||
|
||||
```cpp
|
||||
class transaction
|
||||
{
|
||||
public:
|
||||
explicit transaction(session & sql);
|
||||
|
||||
~transaction();
|
||||
|
||||
void commit();
|
||||
void rollback();
|
||||
|
||||
private:
|
||||
// ...
|
||||
};
|
||||
```
|
||||
|
||||
Note that objects of this class are not notified of other transaction related operations that might be executed by user code explicitly or hidden inside SQL queries. It is not recommended to mix different ways of managing transactions.
|
||||
|
||||
## function into
|
||||
|
||||
The function `into` is used for binding local output data (in other words, it defines where the results of the query are stored).
|
||||
|
||||
```cpp
|
||||
template <typename T>
|
||||
IT into(T & t);
|
||||
|
||||
template <typename T, typename T1>
|
||||
IT into(T & t, T1 p1);
|
||||
|
||||
template <typename T>
|
||||
IT into(T & t, indicator & ind);
|
||||
|
||||
template <typename T, typename T1>
|
||||
IT into(T & t, indicator & ind, T1 p1);
|
||||
|
||||
template <typename T>
|
||||
IT into(T & t, std::vector<indicator> & ind);
|
||||
```
|
||||
|
||||
Example:
|
||||
|
||||
```cpp
|
||||
int count;
|
||||
sql << "select count(*) from person", into(count);
|
||||
```
|
||||
|
||||
See [Binding local dat](exchange.html#bind_local) for more examples
|
||||
|
||||
## function use
|
||||
|
||||
The function `use` is used for binding local input data (in other words, it defines where the parameters of the query come from).
|
||||
|
||||
```cpp
|
||||
template <typename T>
|
||||
*IT* use(T & t);
|
||||
|
||||
template <typename T, typename T1>
|
||||
*IT* use(T & t, T1 p1);
|
||||
|
||||
template <typename T>
|
||||
*IT* use(T & t, indicator & ind);
|
||||
|
||||
template <typename T, typename T1>
|
||||
*IT* use(T & t, indicator & ind, T1 p1);
|
||||
|
||||
template <typename T>
|
||||
*IT* use(T & t, std::vector<indicator> const & ind);
|
||||
|
||||
template <typename T, typename T1>
|
||||
*IT* use(T & t, std::vector<indicator> const & ind, T1 p1);
|
||||
```
|
||||
|
||||
Example:
|
||||
|
||||
```cpp
|
||||
int val = 7;
|
||||
sql << "insert into numbers(val) values(:val)", use(val);
|
||||
```
|
||||
|
||||
See [Binding local data](exchange.html#bind_local) for more examples.
|
||||
|
||||
## class statement
|
||||
|
||||
The `statement` class encapsulates the prepared statement.
|
||||
|
||||
```cpp
|
||||
class statement
|
||||
{
|
||||
public:
|
||||
statement(session & s);
|
||||
statement(*IT* const & prep);
|
||||
~statement();
|
||||
|
||||
statement(statement const & other);
|
||||
void operator=(statement const & other);
|
||||
|
||||
void alloc();
|
||||
void bind(values & v);
|
||||
void exchange(*IT* const & i);
|
||||
void exchange(*IT* const & u);
|
||||
void clean_up();
|
||||
void bind_clean_up();
|
||||
|
||||
void prepare(std::string const & query);
|
||||
void define_and_bind();
|
||||
|
||||
bool execute(bool withDataExchange = false);
|
||||
long long get_affected_rows();
|
||||
bool fetch();
|
||||
|
||||
bool got_data() const;
|
||||
|
||||
void describe();
|
||||
void set_row(row * r);
|
||||
void exchange_for_rowset(*IT* const & i);
|
||||
|
||||
details::statement_backend * get_backend();
|
||||
};
|
||||
```
|
||||
|
||||
This class contains the following members:
|
||||
|
||||
* Constructor accepting the `session` object. This can be used for later query preparation. Example:
|
||||
|
||||
```cpp
|
||||
statement stmt(sql);
|
||||
```
|
||||
|
||||
* Constructor accepting the result of using `prepare` on the `session` object, see example provided above for the `session` class.
|
||||
* Copy operations.
|
||||
* `alloc` function, which allocates necessary internal resources.
|
||||
* `bind` function, which is used to bind the `values` object - this is used in the object-relational mapping and normally called automatically.
|
||||
* exchange functions for registering the binding of local data - they expect the result of calling the `into` or `use` functions and are normally invoked automatically.
|
||||
* `clean_up` function for cleaning up resources, normally called automatically.
|
||||
* `bind_clean_up` function for cleaning up any bound references. It allows to keep statement in cache and reuse it later with new references by calling `exchange` for each new bind variable.
|
||||
* `prepare` function for preparing the statement for repeated execution.
|
||||
* `define_and_bind` function for actually executing the registered bindings, normally called automatically.
|
||||
* `execute` function for executing the statement. If its parameter is `false` then there is no data exchange with locally bound variables (this form should be used if later `fetch` of multiple rows is foreseen). Returns `true` if there was at least one row of data returned.
|
||||
* `get_affected_rows` function returns the number of rows affected by the last statement. Returns `-1` if it's not implemented by the backend being used.
|
||||
* `fetch` function for retrieving the next portion of the result. Returns `true` if there was new data.
|
||||
* `got_data` return `true` if the most recent execution returned any rows.
|
||||
* `describe` function for extracting the type information for the result (**Note:** no data is exchanged). This is normally called automatically and only when dynamic resultset binding is used.
|
||||
* `set_row` function for associating the `statement` and `row` objects, normally called automatically.
|
||||
* `exchange_for_rowset` as a special case for binding `rowset` objects.
|
||||
* `get_backend` function that returns the internal pointer to the concrete backend implementation of the statement object. This is provided for advanced users that need access to the functionality that is not otherwise available.
|
||||
|
||||
See [Statement preparation and repeated execution](statements.html#preparation) for example uses.
|
||||
|
||||
Most of the functions from the `statement` class interface are called automatically, but can be also used explicitly. See [Interfaces](interfaces) for the description of various way to use this interface.
|
||||
|
||||
## class procedure
|
||||
|
||||
The `procedure` class encapsulates the call to the stored procedure and is aimed for higher portability of the client code.
|
||||
|
||||
```cpp
|
||||
class procedure
|
||||
{
|
||||
public:
|
||||
procedure(*IT* const & prep);
|
||||
|
||||
bool execute(bool withDataExchange = false);
|
||||
bool fetch();
|
||||
bool got_data() const;
|
||||
};
|
||||
```
|
||||
|
||||
The constructor expects the result of using `prepare` on the `session` object.
|
||||
|
||||
See [Stored procedures](statements.html#procedures) for examples.
|
||||
|
||||
## class type_conversion
|
||||
|
||||
The `type_conversion` class is a traits class that is supposed to be provided (specialized) by the user for defining conversions to and from one of the basic SOCI types.
|
||||
|
||||
```cpp
|
||||
template <typename T>
|
||||
struct type_conversion
|
||||
{
|
||||
typedef T base_type;
|
||||
|
||||
static void from_base(base_type const & in, indicator ind, T & out);
|
||||
|
||||
static void to_base(T const & in, base_type & out, indicator & ind);
|
||||
};
|
||||
```
|
||||
|
||||
Users are supposed to properly implement the `from_base` and `to_base` functions in their specializations of this template class.
|
||||
|
||||
See [Extending SOCI to support custom (user-defined) C++ types](exchange.html#custom_types).
|
||||
|
||||
## class row
|
||||
|
||||
The `row` class encapsulates the data and type information retrieved for the single row when the dynamic rowset binding is used.
|
||||
|
||||
```cpp
|
||||
class row
|
||||
{
|
||||
public:
|
||||
row();
|
||||
~row();
|
||||
|
||||
void uppercase_column_names(bool forceToUpper);
|
||||
|
||||
std::size_t size() const;
|
||||
|
||||
indicator get_indicator(std::size_t pos) const;
|
||||
indicator get_indicator(std::string const & name) const;
|
||||
|
||||
column_properties const & get_properties (std::size_t pos) const;
|
||||
column_properties const & get_properties (std::string const & name) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::size_t pos) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::size_t pos, T const & nullValue) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::string const & name) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::string const & name, T const & nullValue) const;
|
||||
|
||||
template <typename T>
|
||||
row const & operator>>(T & value) const;
|
||||
|
||||
void skip(std::size_t num = 1) const;
|
||||
|
||||
void reset_get_counter() const
|
||||
};
|
||||
```
|
||||
|
||||
This class contains the following members:
|
||||
|
||||
* Default constructor that allows to declare a `row` variable.
|
||||
* `uppercase_column_names` - see the same function in the `session` class.
|
||||
* `size` function that returns the number of columns in the row.
|
||||
* `get_indicator` function that returns the indicator value for the given column (column is specified by position - starting from 0 - or by name).
|
||||
* `get_properties` function that returns the properties of the column given by position (starting from 0) or by name.
|
||||
* `get` functions that return the value of the column given by position or name. If the column contains null, then these functions either return the provided "default" `nullValue` or throw an exception.
|
||||
* `operator>>` for convenience stream-like extraction interface. Subsequent calls to this function are equivalent to calling `get` with increasing position parameter, starting from the beginning.
|
||||
* `skip` and `reset_get_counter` allow to change the order of data extraction for the above operator.
|
||||
|
||||
See [Dynamic resultset binding](exchange.html#dynamic) for examples.
|
||||
|
||||
## class column_properties
|
||||
|
||||
The `column_properties` class provides the type and name information about the particular column in a rowset.
|
||||
|
||||
```cpp
|
||||
class column_properties
|
||||
{
|
||||
public:
|
||||
std::string get_name() const;
|
||||
data_type get_data_type() const;
|
||||
};
|
||||
```
|
||||
|
||||
This class contains the following members:
|
||||
|
||||
* `get_name` function that returns the name of the column.
|
||||
* `get_data_type` that returns the type of the column.
|
||||
|
||||
See [Dynamic resultset binding](exchange.html#dynamic) for examples.
|
||||
|
||||
## class values
|
||||
|
||||
The `values` class encapsulates the data and type information and is used for object-relational mapping.
|
||||
|
||||
```cpp
|
||||
class values
|
||||
{
|
||||
public:
|
||||
values();
|
||||
|
||||
void uppercase_column_names(bool forceToUpper);
|
||||
|
||||
indicator get_indicator(std::size_t pos) const;
|
||||
indicator get_indicator(std::string const & name) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::size_t pos) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::size_t pos, T const & nullValue) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::string const & name) const;
|
||||
|
||||
template <typename T>
|
||||
T get(std::string const & name, T const & nullValue) const;
|
||||
|
||||
template <typename T>
|
||||
values const & operator>>(T & value) const;
|
||||
|
||||
void skip(std::size_t num = 1) const;
|
||||
void reset_get_counter() const;
|
||||
|
||||
template <typename T>
|
||||
void set(std::string const & name, T const & value, indicator indic = i_ok);
|
||||
|
||||
template <typename T>
|
||||
void set(const T & value, indicator indic = i_ok);
|
||||
|
||||
template <typename T>
|
||||
values & operator<<(T const & value);
|
||||
};
|
||||
```
|
||||
|
||||
This class contains the same members as the `row` class (with the same meaning) plus:
|
||||
|
||||
* `set` function for storing values in named columns or in subsequent positions.
|
||||
* `operator<<` for convenience.
|
||||
|
||||
See [Object-relational mapping](exchange.html#object_relational) for examples.
|
||||
|
||||
## class blob
|
||||
|
||||
The `blob` class encapsulates the "large object" functionality.
|
||||
|
||||
```cpp
|
||||
class blob
|
||||
{
|
||||
public:
|
||||
explicit blob(session & s);
|
||||
~blob();
|
||||
|
||||
std::size_t getLen();
|
||||
std::size_t read(std::size_t offset, char * buf, std::size_t toRead);
|
||||
std::size_t write(std::size_t offset, char const * buf, std::size_t toWrite);
|
||||
std::size_t append(char const * buf, std::size_t toWrite);
|
||||
void trim(std::size_t newLen);
|
||||
|
||||
details::blob_backend * get_backend();
|
||||
};
|
||||
```
|
||||
|
||||
This class contains the following members:
|
||||
|
||||
* Constructor associating the `blob` object with the `session` object.
|
||||
* `get_len` function that returns the size of the BLOB object.
|
||||
* `read` function that reads the BLOB data into provided buffer.
|
||||
* `write` function that writes the BLOB data from provided buffer.
|
||||
* `append` function that appends to the existing BLOB data.
|
||||
* `trim` function that truncates the existing data to the new length.
|
||||
* `get_backend` function that returns the internal pointer to the concrete backend implementation of the BLOB object. This is provided for advanced users that need access to the functionality that is not otherwise available.
|
||||
|
||||
See [Large objects (BLOBs)](exchange.html#blob) for more discussion.
|
||||
|
||||
## class rowid
|
||||
|
||||
The `rowid` class encapsulates the "row identifier" object.
|
||||
|
||||
```cpp
|
||||
class rowid
|
||||
{
|
||||
public:
|
||||
explicit rowid(Session & s);
|
||||
~rowid();
|
||||
|
||||
details::rowid_backend * get_backend();
|
||||
};
|
||||
```
|
||||
|
||||
This class contains the following members:
|
||||
|
||||
* Constructor associating the `rowid` object with the `session` object.
|
||||
* `get_backend` function that returns the internal pointer to the concrete backend implementation of the `rowid` object.
|
||||
|
||||
## class backend_factory
|
||||
|
||||
The `backend_factory` class provides the abstract interface for concrete backend factories.
|
||||
|
||||
```cpp
|
||||
struct backend_factory
|
||||
{
|
||||
virtual details::session_backend * make_session(
|
||||
std::string const & connectString) const = 0;
|
||||
};
|
||||
```
|
||||
|
||||
The only member of this class is the `make_session` function that is supposed to create concrete backend implementation of the session object.
|
||||
|
||||
Objects of this type are declared by each backend and should be provided to the constructor of the `session` class. In simple programs users do not need to use this class directly, but the example use is:
|
||||
|
||||
```cpp
|
||||
backend_factory & factory = postgresql;
|
||||
std::string connectionParameters = "dbname=mydb";
|
||||
|
||||
session sql(factory, parameters);
|
||||
```
|
||||
|
||||
## Simple Client Interface
|
||||
|
||||
The simple client interface is provided with other languages in mind, to allow easy integration of the SOCI library with script interpreters and those languages that have the ability to link directly with object files using the "C" calling convention.
|
||||
|
||||
The functionality of this interface is limited and in particular the dynamic rowset description and type conversions are not supported in this release. On the other hand, the important feature of this interface is that it does not require passing pointers to data managed by the user, because all data is handled at the SOCI side. This should make it easier to integrate SOCI with languages that have constrained ability to understand the C type system.
|
||||
|
||||
Users of this interface need to explicitly `#include <soci-simple.h>`.
|
||||
|
||||
```c
|
||||
typedef void * session_handle;
|
||||
session_handle soci_create_session(char const * connectionString);
|
||||
void soci_destroy_session(session_handle s);
|
||||
|
||||
void soci_begin(session_handle s);
|
||||
void soci_commit(session_handle s);
|
||||
void soci_rollback(session_handle s);
|
||||
|
||||
int soci_session_state(session_handle s);
|
||||
char const * soci_session_error_message(session_handle s);
|
||||
```
|
||||
|
||||
The functions above provide the *session* abstraction with the help of opaque handle. The `soci_session_state` function returns `1` if there was no error during the most recently executed function and `0` otherwise, in which case the `soci_session_error_message` can be used to obtain a human-readable error description.
|
||||
|
||||
Note that the only function that cannot report all errors this way is `soci_create_session`, which returns `NULL` if it was not possible to create an internal object representing the session. However, if the proxy object was created, but the connection could not be established for whatever reason, the error message can be obtained in the regular way.
|
||||
|
||||
```c
|
||||
typedef void *blob_handle;
|
||||
blob_handle soci_create_blob(session_handle s);
|
||||
void soci_destroy_blob(blob_handle b);
|
||||
|
||||
int soci_blob_get_len(blob_handle b);
|
||||
int soci_blob_read(blob_handle b, int offset, char *buf, int toRead);
|
||||
int soci_blob_write(blob_handle b, int offset, char const *buf, int toWrite);
|
||||
int soci_blob_append(blob_handle b, char const *buf, int toWrite);
|
||||
int soci_blob_trim(blob_handle b, int newLen);
|
||||
|
||||
int soci_blob_state(blob_handle b);
|
||||
char const * soci_blob_error_message(blob_handle b);
|
||||
```
|
||||
|
||||
The functions above provide the *blob* abstraction with the help of opaque handle. The `soci_blob_state` function returns `1` if there was no error during the most recently executed function and `0` otherwise, in which case the `soci_session_error_message` can be used to obtain a human-readable error description.
|
||||
|
||||
For easy error testing, functions `soci_blob_read`, `soci_blob_write`, `soci_blob_append`, and `soci_blob_trim` return `-1` in case of error and `soci_session_error_message` can be used to obtain a human-readable error description.
|
||||
|
||||
Note that the only function that cannot report all errors this way is `soci_create_blob`, which returns `NULL` if it was not possible to create an internal object representing the blob.
|
||||
|
||||
```c
|
||||
typedef void * statement_handle;
|
||||
statement_handle soci_create_statement(session_handle s);
|
||||
void soci_destroy_statement(statement_handle st);
|
||||
|
||||
int soci_statement_state(statement_handle s);
|
||||
char const * soci_statement_error_message(statement_handle s);
|
||||
```
|
||||
|
||||
The functions above create and destroy the statement object. If the statement cannot be created by the `soci_create_statement` function, the error condition is set up in the related session object; for all other functions the error condition is set in the statement object itself.
|
||||
|
||||
```c
|
||||
int soci_into_string (statement_handle st);
|
||||
int soci_into_int (statement_handle st);
|
||||
int soci_into_long_long(statement_handle st);
|
||||
int soci_into_double (statement_handle st);
|
||||
int soci_into_date (statement_handle st);
|
||||
int soci_into_blob (statement_handle st);
|
||||
|
||||
int soci_into_string_v (statement_handle st);
|
||||
int soci_into_int_v (statement_handle st);
|
||||
int soci_into_long_long_v(statement_handle st);
|
||||
int soci_into_double_v (statement_handle st);
|
||||
int soci_into_date_v (statement_handle st);
|
||||
```
|
||||
|
||||
These functions create new data items for storing query results (*into elements*). These elements can be later identified by their position, which is counted from 0. For convenience, these function return the position of the currently added element. In case of error, `-1` is returned and the error condition is set in the statement object.
|
||||
|
||||
The `_v` versions create a `vector` into elements, which can be used
|
||||
to retrieve whole arrays of results.
|
||||
|
||||
```c
|
||||
int soci_get_into_state(statement_handle st, int position);
|
||||
int soci_get_into_state_v(statement_handle st, int position, int index);
|
||||
```
|
||||
|
||||
This function returns `1` if the into element at the given position has non-null value and `0` otherwise. The `_v` version works with `vector` elements and expects an array index.
|
||||
|
||||
```c
|
||||
char const * soci_get_into_string (statement_handle st, int position);
|
||||
int soci_get_into_int (statement_handle st, int position);
|
||||
long long soci_get_into_long_long(statement_handle st, int position);
|
||||
double soci_get_into_double (statement_handle st, int position);
|
||||
char const * soci_get_into_date (statement_handle st, int position);
|
||||
blob_handle soci_get_into_blob (statement_handle st, int position);
|
||||
|
||||
char const * soci_get_into_string_v (statement_handle st, int position, int index);
|
||||
int soci_get_into_int_v (statement_handle st, int position, int index);
|
||||
long long soci_get_into_long_long_v(statement_handle st, int position, int index);
|
||||
double soci_get_into_double_v (statement_handle st, int position, int index);
|
||||
char const * soci_get_into_date_v (statement_handle st, int position, int index);
|
||||
```
|
||||
|
||||
The functions above allow to retrieve the current value of the given into element.
|
||||
|
||||
**Note:** The `date` function returns the date value in the "`YYYY MM DD HH mm ss`" string format.
|
||||
|
||||
```c
|
||||
void soci_use_string (statement_handle st, char const * name);
|
||||
void soci_use_int (statement_handle st, char const * name);
|
||||
void soci_use_long_long(statement_handle st, char const * name);
|
||||
void soci_use_double (statement_handle st, char const * name);
|
||||
void soci_use_date (statement_handle st, char const * name);
|
||||
void soci_use_blob (statement_handle st, char const * name);
|
||||
|
||||
void soci_use_string_v (statement_handle st, char const * name);
|
||||
void soci_use_int_v (statement_handle st, char const * name);
|
||||
void soci_use_long_long_v(statement_handle st, char const * name);
|
||||
void soci_use_double_v (statement_handle st, char const * name);
|
||||
void soci_use_date_v (statement_handle st, char const * name);
|
||||
```
|
||||
|
||||
The functions above allow to create new data elements that will be used to provide data to the query (*use elements*). The new elements can be later identified by given name, which must be unique for the given statement.
|
||||
|
||||
```c
|
||||
void soci_set_use_state(statement_handle st, char const * name, int state);
|
||||
```
|
||||
|
||||
The `soci_set_use_state` function allows to set the state of the given use element. If the `state` parameter is set to non-zero the use element is considered non-null (which is also the default state after creating the use element).
|
||||
|
||||
```c
|
||||
int soci_use_get_size_v(statement_handle st);
|
||||
void soci_use_resize_v (statement_handle st, int new_size);
|
||||
```
|
||||
|
||||
These functions get and set the size of vector use elements (see comments for vector into elements above).
|
||||
|
||||
```c
|
||||
void soci_set_use_string (statement_handle st, char const * name, char const * val);
|
||||
void soci_set_use_int (statement_handle st, char const * name, int val);
|
||||
void soci_set_use_long_long(statement_handle st, char const * name, long long val);
|
||||
void soci_set_use_double (statement_handle st, char const * name, double val);
|
||||
void soci_set_use_date (statement_handle st, char const * name, char const * val);
|
||||
void soci_set_use_blob (statement_handle st, char const * name, blob_handle blob);
|
||||
|
||||
void soci_set_use_state_v (statement_handle st, char const * name, int index, int state);
|
||||
void soci_set_use_string_v (statement_handle st, char const * name, int index, char const * val);
|
||||
void soci_set_use_int_v (statement_handle st, char const * name, int index, int val);
|
||||
void soci_set_use_long_long_v(statement_handle st, char const * name, int index, long long val);
|
||||
void soci_set_use_double_v (statement_handle st, char const * name, int index, double val);
|
||||
void soci_set_use_date_v (statement_handle st, char const * name, int index, char const * val);
|
||||
```
|
||||
|
||||
The functions above set the value of the given use element, for both single and vector elements.
|
||||
|
||||
**Note:** The expected format for the data values is "`YYYY MM DD HH mm ss`".
|
||||
|
||||
```c
|
||||
int soci_get_use_state (statement_handle st, char const * name);
|
||||
char const * soci_get_use_string (statement_handle st, char const * name);
|
||||
int soci_get_use_int (statement_handle st, char const * name);
|
||||
long long soci_get_use_long_long(statement_handle st, char const * name);
|
||||
double soci_get_use_double (statement_handle st, char const * name);
|
||||
char const * soci_get_use_date (statement_handle st, char const * name);
|
||||
blob_handle soci_get_use_blob (statement_handle st, char const * name);
|
||||
```
|
||||
|
||||
These functions allow to inspect the state and value of named use elements.
|
||||
|
||||
***Note:*** these functions are provide only for single use elements, not for vectors; the rationale for this is that modifiable use elements are not supported for bulk operations.
|
||||
|
||||
```c
|
||||
void soci_prepare(statement_handle st, char const * query);
|
||||
int soci_execute(statement_handle st, int withDataExchange);
|
||||
int soci_fetch(statement_handle st);
|
||||
int soci_got_data(statement_handle st);
|
||||
```
|
||||
|
||||
The functions above provide the core execution functionality for the statement object and their meaning is equivalent to the respective functions in the core C++ interface described above.
|
||||
Reference in New Issue
Block a user