php man page for mysql_error

MYSQL_ERROR(3)								 1							    MYSQL_ERROR(3)

mysql_error - Returns the text of the error message from previous MySQL operation

SYNOPSIS
       Warning

	      This  extension  is deprecated as of PHP 5.5.0, and will be removed in the future. Instead, the MySQLi or PDO_MySQL extension should
	      be used. See also MySQL: choosing an API guide and related FAQ for more information. Alternatives to this function include:

		     omysqli_error(3)

		     o PDO::errorInfo

       string mysql_error ([resource  $link_identifier = NULL])

DESCRIPTION
	Returns the error text from the last MySQL function. Errors coming back from the MySQL database backend no longer issue warnings. Instead,
       use  mysql_error(3)  to	retrieve the error text. Note that this function only returns the error text from the most recently executed MySQL
       function (not including mysql_error(3) and mysql_errno(3)), so if you want to use it, make sure you check the value before calling  another
       MySQL function.

	      o $
		link_identifier  -The  MySQL  connection.  If  the  link  identifier is not specified, the last link opened by mysql_connect(3) is
		assumed. If no such link is found, it will try to create one as if mysql_connect(3) was called with no arguments. If no connection
		is found or established, an E_WARNING level error is generated.

	Returns the error text from the last MySQL function, or '' (empty string) if no error occurred.

       Example #1

	      mysql_error(3) example

	      <?php
	      $link = mysql_connect("localhost", "mysql_user", "mysql_password");

	      mysql_select_db("nonexistentdb", $link);
	      echo mysql_errno($link) . ": " . mysql_error($link). "
";

	      mysql_select_db("kossu", $link);
	      mysql_query("SELECT * FROM nonexistenttable", $link);
	      echo mysql_errno($link) . ": " . mysql_error($link) . "
";
	      ?>

	      The above example will output something similar to:

	      1049: Unknown database 'nonexistentdb'
	      1146: Table 'kossu.nonexistenttable' doesn't exist

       mysql_errno(3), MySQL error codes.

PHP Documentation Group 													    MYSQL_ERROR(3)