PHP，MySQL UNION查询错误

Question

I am having a problem trying to debug this query using PHP/MySQl-AJAX: The variable $param is the result of a AJAX call on a form textbox. In essence I am trying to generate a dynamic search over three database tables which unfortunately have different fields (hence the concat). The data are addresses of jobs which have a spatial location (for the first two tables) generated using different methods, the last table is non spatial data.

            $fetch = "(SELECT JobNo AS JobNo, CONCAT(Title1, '-', Title2, '-', Title3) AS Description, 'Hurricane' as type FROM Hurricanev2 WHERE Title1 REGEXP '$param' OR Title2 REGEXP '$param' OR Title3 REGEXP '$param') 
       UNION ALL
       (SELECT jobNo AS JobNo, description As Description, address As Geocoded_address, 'geocoded' as type FROM jr WHERE description REGEXP '$param' OR address REGEXP '$param')
       UNION ALL
       (SELECT job As JobNo, description As Description, 'plan' as type FROM register WHERE description REGEXP '$param')";


    while ( $row = mysql_fetch_object( $fetch ) ) {

        $sResults .= '<tr>';
        $sResults .= '<td>' . $row['JobNo'] . '</td>';
        $sResults .= '<td>' . $row['Description'] . '</td></tr>';
    }

thanks in advance

Answer 1

You can't union the result sets which has different number of columns.

Try the following;

$fetch = "(SELECT JobNo AS JobNo, CONCAT(Title1, '-', Title2, '-', Title3) AS Description, 'Hurricane' as type, 'extra' FROM Hurricanev2 WHERE Title1 REGEXP '$param' OR Title2 REGEXP '$param' OR Title3 REGEXP '$param') 
   UNION ALL
   (SELECT jobNo AS JobNo, description As Description, address As Geocoded_address, 'geocoded' as type FROM jr WHERE description REGEXP '$param' OR address REGEXP '$param')
   UNION ALL
   (SELECT job As JobNo, description As Description, 'plan' as type, 'extra' FROM register WHERE description REGEXP '$param')";

Answer 2

for UNION you need to have the same number of columns for each SELECT. Try adding in an extra null on first and last SELECT to even in out.