When passing an array to $adapter->quoteInto() as the second argument, the function changes the values of the array. For example: // names = Array ( [0] => php [1] => google [2] => working ) $names = array( 'php', 'google', 'working' ); $where = $dba->quoteInto('name IN ', $names) // print the existing array print_r($names); // prints out // Array ( [0] => 'php' [1] => 'google' [2] => 'working' ) Notice quoteInto() has now added single quotes to each value in the array, which is unexpected behavior. This was specifically recreated using the MySQL db adapter using Zend _Db_Table.