MySQL 5.1 Database Reference Guide :: 26.1.9.4 Connection Parameters

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26.1.9.4. Connection Parameters

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You can specify the following parameters for MyODBC in the [Data Source Name] section of an ODBC.INI file or through the InConnectionString argument in the SQLDriverConnect() call.

Parameter	Default Value	Comment
`user`	ODBC (on Windows)	The username used to connect to MySQL.
`server`	`localhost`	The hostname of the MySQL server.
`database`		The default database.
`option`	0	Options that specify how MyODBC should work. See below.
`port`	3306	The TCP/IP port to use if `server` is not `localhost`.
`stmt`		A statement to execute when connecting to MySQL.
`password`		The password for the `user` account on `server`.
`socket`		The Unix socket file or Windows named pipe to connect to if `server` is `localhost`.

The option argument is used to tell MyODBC that the client isn't 100% ODBC compliant. On Windows, you normally select options by toggling the checkboxes in the connection screen, but you can also select them in the option argument. The following options are listed in the order in which they appear in the MyODBC connect screen:

Value	Description
1	The client can't handle that MyODBC returns the real width of a column.
2	The client can't handle that MySQL returns the true value of affected rows. If this flag is set, MySQL returns “found rows” instead. You must have MySQL 3.21.14 or newer to get this to work.
4	Make a debug log in `c:\myodbc.log`. This is the same as putting `MYSQL_DEBUG=d:t:O,c::\myodbc.log` in `AUTOEXEC.BAT`. (On Unix, the file is `/tmp/myodbc.log`.)
8	Don't set any packet limit for results and parameters.
16	Don't prompt for questions even if driver would like to prompt.
32	Enable or disable the dynamic cursor support. (Not allowed in MyODBC 2.50.)
64	Ignore use of database name in `db_name.tbl_name.col_name`.
128	Force use of ODBC manager cursors (experimental).
256	Disable the use of extended fetch (experimental).
512	Pad `CHAR` columns to full column length.
1024	`SQLDescribeCol()` returns fully qualified column names.
2048	Use the compressed client/server protocol.
4096	Tell server to ignore space after function name and before ‘`(`’ (needed by PowerBuilder). This makes all function names keywords.
8192	Connect with named pipes to a mysqld server running on NT.
16384	Change `LONGLONG` columns to `INT` columns (some applications can't handle `LONGLONG`).
32768	Return 'user' as `Table_qualifier` and `Table_owner` from `SQLTables` (experimental).
65536	Read parameters from the `[client]` and `[odbc]` groups from `my.cnf`.
131072	Add some extra safety checks (should not be needed but...).
262144	Disable transactions.
524288	Enable query logging to `c:\myodbc.sql`(`/tmp/myodbc.sql`) file. (Enabled only in debug mode.)
1048576	Do not cache the results locally in the driver, instead read from server (`mysql_use_result()`). This works only for forward-only cursors. This option is very important in dealing with large tables when you don't want the driver to cache the entire result set.
2097152	Force the use of `Forward-only` cursor type. In case of applications setting the default static/dynamic cursor type, and one wants the driver to use non-cache result sets, then this option ensures the forward-only cursor behavior.

To select multiple options, add together their values. For example, setting option to 12 (4+8) gives you debugging without packet limits.

The default myodbc3.dll is compiled for optimal performance. If you want to debug MyODBC 3.51 (for example, to enable tracing), you should instead use myodbc3d.dll. To install this file, copy myodbc3d.dll over the installed myodbc3.dll file. Make sure to revert back to the release version of the driver DLL once you are done with the debugging because the debug version may cause performance issues. Note that the myodbc3d.dll isn't included in MyODBC 3.51.07 through 3.51.11. If you are using one of these versions, you should copy that DLL from a previous version (for example, 3.51.06).

For MyODBC 2.50, myodbc.dll and myodbcd.dll are used instead.

The following table shows some recommended option values for various configurations:

Configuration	Option Value
Microsoft Access	3
Microsoft Visual Basic	3
Large tables with too many rows	2049
Driver trace generation (Debug mode)	4
Query log generation (Debug mode)	524288
Generate driver trace as well as query log (Debug mode)	524292
Large tables with no-cache results	3145731

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