# Predefined Constants

The constants below are defined by this extension, and will only be available when the extension has either been compiled into PHP or dynamically loaded at runtime.

It is possible to specify additional client flags for the mysql_connect() and mysql_pconnect() functions. The following constants are defined:

MySQL client constants
Constant | Description
--- | ---
`MYSQL_CLIENT_COMPRESS` | Use compression protocol
`MYSQL_CLIENT_IGNORE_SPACE` | Allow space after function names
`MYSQL_CLIENT_INTERACTIVE` | Allow interactive_timeout seconds (instead of wait_timeout) of inactivity before closing the connection.
`MYSQL_CLIENT_SSL` | Use SSL encryption. This flag is only available with version 4.x of the MySQL client library or newer. Version 3.23.x is bundled both with PHP 4 and Windows binaries of PHP 5.

The function mysql_fetch_array() uses a constant for the different types of result arrays. The following constants are defined:

MySQL fetch constants
Constant | Description
--- | ---
`MYSQL_ASSOC` | Columns are returned into the array having the fieldname as the array index.
`MYSQL_BOTH` | Columns are returned into the array having both a numerical index and the fieldname as the array index.
`MYSQL_NUM` | Columns are returned into the array having a numerical index to the fields. This index starts with 0, the first field in the result.