mysqlpp::Connection Class Reference

Manages the connection to the database server. More...

#include <connection.h>

Inheritance diagram for mysqlpp::Connection:

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Collaboration diagram for mysqlpp::Connection:

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List of all members.

Public Member Functions

 Connection (bool te=true)
 Create object without connecting to the database server.
 Connection (const char *db, const char *server=0, const char *user=0, const char *password=0, unsigned int port=0)
 Create object and connect to database server in one step.
 Connection (const Connection &other)
 Establish a new connection using the same parameters as an existing connection.
virtual ~Connection ()
 Destroy object.
std::string client_version () const
 Get version of library underpinning the current database driver.
virtual bool connect (const char *db=0, const char *server=0, const char *user=0, const char *password=0, unsigned int port=0)
 Connect to database after object is created.
bool connected () const
 Returns true if connection was established successfully.
ulonglong count_rows (const std::string &table)
 Returns the number of rows in a table.
bool create_db (const std::string &db)
 Ask the database server to create a database.
void disconnect ()
 Drop the connection to the database server.
DBDriverdriver ()
 Returns a reference to the current database driver.
bool drop_db (const std::string &db)
 Asks the database server to drop (destroy) a database.
int errnum ()
 Return last error number associated with this connection.
const char * error () const
 Return error message for last error associated with this connection.
std::string ipc_info () const
 Get information about the IPC connection to the database server.
bool kill (unsigned long tid) const
 Kill a database server thread.
 operator private_bool_type () const
 Test whether any error has occurred within the object.
Connectionoperator= (const Connection &rhs)
 Copy an existing Connection object's state into this object.
bool ping ()
 "Pings" the database server
int protocol_version () const
 Returns version number of the protocol the database driver uses to communicate with the server.
Query query (const char *qstr=0)
 Return a new query object.
Query query (const std::string &qstr)
 Return a new query object.
bool select_db (const std::string &db)
 Change to a different database managed by the database server we are connected to.
std::string server_version () const
 Get the database server's version string.
bool set_option (Option *o)
 Sets a connection option.
bool shutdown ()
 Ask database server to shut down.
std::string server_status () const
 Returns information about database server's status.
unsigned long thread_id ()
 Returns the database server's thread ID for this connection.

Static Public Member Functions

static bool thread_aware ()
 Returns true if both MySQL++ and database driver we're using were compiled with thread awareness.
static void thread_end ()
 Tells the underlying database driver that this thread is done using the library.
static bool thread_start ()
 Tells the underlying database driver that the current thread is now using its services.

Protected Member Functions

void build_error_message (const char *core)
 Build an error message in the standard form used whenever one of the methods can't succeed because we're not connected to the database server.
void copy (const Connection &other)
 Establish a new connection as a copy of an existing one.
bool parse_ipc_method (const char *server, std::string &host, unsigned int &port, std::string &socket_name)
 Extract elements from the server parameter in formats suitable for passing to DBDriver::connect().

Protected Attributes

std::string error_message_
 MySQL++ specific error, if any.

Detailed Description

Manages the connection to the database server.

This class is a thick wrapper around DBDriver, adding high-level error handling, utility functions, and abstraction away from underlying C API details.


Constructor & Destructor Documentation

mysqlpp::Connection::Connection ( bool  te = true  ) 

Create object without connecting to the database server.

Parameters:
te if true, exceptions are thrown on errors

mysqlpp::Connection::Connection ( const char *  db,
const char *  server = 0,
const char *  user = 0,
const char *  password = 0,
unsigned int  port = 0 
)

Create object and connect to database server in one step.

This constructor allows you to most fully specify the options used when connecting to the database server.

Parameters:
db name of database to select upon connection
server specifies the IPC method and parameters for contacting the server; see below for details
user user name to log in under, or 0 to use the user name this program is running under
password password to use when logging in
port TCP port number database server is listening on, or 0 to use default value; note that you may also give this as part of the server parameter
The server parameter can be any of several different forms:

mysqlpp::Connection::Connection ( const Connection other  ) 

Establish a new connection using the same parameters as an existing connection.

Parameters:
other existing Connection object


Member Function Documentation

bool mysqlpp::Connection::connect ( const char *  db = 0,
const char *  server = 0,
const char *  user = 0,
const char *  password = 0,
unsigned int  port = 0 
) [virtual]

Connect to database after object is created.

It's better to use the connect-on-create constructor if you can. See its documentation for the meaning of these parameters.

If you call this method on an object that is already connected to a database server, the previous connection is dropped and a new connection is established.

bool mysqlpp::Connection::connected (  )  const

Returns true if connection was established successfully.

Returns:
true if connection was established successfully

void mysqlpp::Connection::copy ( const Connection other  )  [protected]

Establish a new connection as a copy of an existing one.

Parameters:
other the connection to copy

ulonglong mysqlpp::Connection::count_rows ( const std::string &  table  ) 

Returns the number of rows in a table.

Parameters:
table name of table whose rows you want counted
This is syntactic sugar for a SELECT COUNT(*) FROM table SQL query.

bool mysqlpp::Connection::create_db ( const std::string &  db  ) 

Ask the database server to create a database.

Parameters:
db name of database to create
Returns:
true if database was created successfully

bool mysqlpp::Connection::drop_db ( const std::string &  db  ) 

Asks the database server to drop (destroy) a database.

Parameters:
db name of database to destroy
Returns:
true if database was dropped successfully

const char * mysqlpp::Connection::error (  )  const

Return error message for last error associated with this connection.

Returns either a MySQL++-specific error message if one exists, or one from the current database driver otherwise.

std::string mysqlpp::Connection::ipc_info (  )  const

Get information about the IPC connection to the database server.

String contains info about type of connection (e.g. TCP/IP, named pipe, Unix socket...) and the server hostname.

bool mysqlpp::Connection::kill ( unsigned long  tid  )  const

Kill a database server thread.

Parameters:
tid ID of thread to kill
See also:
thread_id()

mysqlpp::Connection::operator private_bool_type (  )  const [inline]

Test whether any error has occurred within the object.

Allows the object to be used in bool context, like this:








        /// 

Prior to MySQL++ v3, the object was always falsy when we weren't connected. Now a true return simply indicates a lack of errors. If you've been using this to test for whether the connection is still up, you need to call connected() instead.

bool mysqlpp::Connection::ping (  ) 

"Pings" the database server

Return values:
true if server is responding
false if either we already know the connection is down and cannot re-establish it, or if the server did not respond to the ping and we could not re-establish the connection.

Query mysqlpp::Connection::query ( const std::string &  qstr  ) 

Return a new query object.

Parameters:
qstr initial query string

Query mysqlpp::Connection::query ( const char *  qstr = 0  ) 

Return a new query object.

The returned query object is tied to this connection object, so when you call a method like execute() on that object, the query is sent to the server this object is connected to.

Parameters:
qstr an optional query string for populating the new Query object

bool mysqlpp::Connection::select_db ( const std::string &  db  ) 

Change to a different database managed by the database server we are connected to.

Parameters:
db database to switch to
Return values:
true if we changed databases successfully

bool mysqlpp::Connection::set_option ( Option o  ) 

Sets a connection option.

Parameters:
o pointer to any derivative of Option allocated on the heap
Objects passed to this method and successfully set will be released when this Connection object is destroyed. If an error occurs while setting the option the object will be deleted immediately.

Because there are so many Option subclasses, the actual effect of this function has a wide range. This mechanism abstracts away many things that are unrelated down at the database driver level, hiding them behind a coherent, type-safe interface.

The rules about which options can be set, when, are up to the underlying database driver. Some must be set before the connection is established because they can only be used during that connection setup process. Others can be set at any time after the connection comes up. If you get it wrong, you'll get a BadOption exception.

Return values:
true if option was successfully set

unsigned long mysqlpp::Connection::thread_id (  ) 

Returns the database server's thread ID for this connection.

This has nothing to do with threading on the client side. The only thing you can do with this value is pass it to kill().

bool mysqlpp::Connection::thread_start (  )  [static]

Tells the underlying database driver that the current thread is now using its services.

It's not necessary to call this from the thread that creates the connection as it's done automatically. This method exists for times when multiple threads may use this object; it allows the underlying database driver to set up any per-thread data structures it needs.

The MySQL++ user manual's chapter on threads details two major strategies for dealing with connections in the face of threads. The Connection-per-thread option frees you from ever having to call this method. The other documented strategy is to use ConnectionPool, which opens the possibility for one thread to create a connection that another uses, so you do need to call this method in that case, or with any other similar strategy.

Return values:
True if there was no problem


The documentation for this class was generated from the following files:
Generated on 20 Jun 2013 for MySQL++ by  doxygen 1.4.7