使用PHP修改SQL SELECT语句

Question

How best to alter a SQL SELECT statment's field list to a COUNT(*) using PHP?

e.g

SELECT blah, blah, blah FROM tbl_blah WHERE blah;

to

SELECT COUNT(*) FROM tbl_blah WHERE blah

I have considered mysql_num_rows... but I am pretty sure it would be more efficient to edit the statement. I am guessing it could be solved with a regex expression... :S

Answer 1

You can do this using preg_replace():

<?php
$sql = "SELECT blah, blah, blah FROM tbl_blah WHERE blah;";

$newSql = preg_replace(
    "/^SELECT (.*) FROM (.*)$/",
    "SELECT COUNT(*) FROM $2",
    $sql);

echo $newSql;
// SELECT COUNT(*) FROM tbl_blah WHERE blah;
?>