The behaviour of these functions is affected by settings in php.ini.
| Name | Default | Changeable | Changelog | 
|---|---|---|---|
| odbc.default_db * | NULL | PHP_INI_ALL | |
| odbc.default_user * | NULL | PHP_INI_ALL | |
| odbc.default_pw * | NULL | PHP_INI_ALL | |
| odbc.allow_persistent | "1" | PHP_INI_SYSTEM | |
| odbc.check_persistent | "1" | PHP_INI_SYSTEM | |
| odbc.max_persistent | "-1" | PHP_INI_SYSTEM | |
| odbc.max_links | "-1" | PHP_INI_SYSTEM | |
| odbc.defaultlrl | "4096" | PHP_INI_ALL | |
| odbc.defaultbinmode | "1" | PHP_INI_ALL | |
| odbc.default_cursortype | "3" | PHP_INI_ALL | Available as of PHP 5.3.0 | 
For further details and definitions of the PHP_INI_* modes, see the Where a configuration setting may be set.Note: Entries marked with * are not implemented yet.
Here's a short explanation of the configuration directives.
odbc.default_db
    string
   ODBC data source to use if none is specified in odbc_connect() or odbc_pconnect().
odbc.default_user
    string
   User name to use if none is specified in odbc_connect() or odbc_pconnect().
odbc.default_pw
    string
   Password to use if none is specified in odbc_connect() or odbc_pconnect().
odbc.allow_persistent
    boolean
   Whether to allow persistent ODBC connections.
odbc.check_persistent
    boolean
   Check that a connection is still valid before reuse.
odbc.max_persistent
    integer
   The maximum number of persistent ODBC connections per process.
odbc.max_links
    integer
   The maximum number of ODBC connections per process, including persistent connections.
odbc.defaultlrl
    integer
   Handling of LONG fields. Specifies the number of bytes returned to variables.
When an integer is used, the value is measured in bytes. Shorthand notation, as described in this FAQ, may also be used.odbc.defaultbinmode
    integer
   Handling of binary data.
odbc.default_cursortype
    integer
   
     Controls the ODBC cursor model.
     Possible values are SQL_CURSOR_FORWARD_ONLY,
     SQL_CURSOR_KEYSET_DRIVEN,
     SQL_CURSOR_DYNAMIC and
     SQL_CURSOR_STATIC (default).