(PECL ibm_db2 >= 1.0.0)
db2_conn_error — Returns a string containing the SQLSTATE returned by the last connection attempt
$connection
  ] )
   db2_conn_error() returns an SQLSTATE value representing
   the reason the last attempt to connect to a database failed. As
   db2_connect() returns FALSE in the event of a failed
   connection attempt, you do not pass any parameters to
   db2_conn_error() to retrieve the SQLSTATE value.
  
   If, however, the connection was successful but becomes invalid over time,
   you can pass the connection parameter to retrieve
   the SQLSTATE value for a specific connection.
  
   To learn what the SQLSTATE value means, you can issue the following command
   at a DB2 Command Line Processor prompt:
   db2 '? . You
   can also call db2_conn_errormsg() to retrieve an
   explicit error message and the associated SQLCODE value.
  sqlstate-value'
connectionA connection resource associated with a connection that initially succeeded, but which over time became invalid.
Returns the SQLSTATE value resulting from a failed connection attempt. Returns an empty string if there is no error associated with the last connection attempt.
Example #1 Retrieving an SQLSTATE value for a failed connection attempt
The following example demonstrates how to return an SQLSTATE value after deliberately passing invalid parameters to db2_connect().
<?php
$conn = db2_connect('badname', 'baduser', 'badpassword');
if (!$conn) {
    print "SQLSTATE value: " . db2_conn_error();
}
?>
The above example will output:
SQLSTATE value: 08001