mysql join default value

Question

I've been trying to use the IsNull() function to ensure that there is a value for a field.

    $result = mysql_query("
SELECT crawled.id,IsNull(sranking.score,0) as Score,crawled.url,crawled.title,crawled.blurb
FROM crawled
LEFT JOIN sranking ON crawled.id = sranking.sid
WHERE crawled.body LIKE '%".$term."%'
ORDER BY Score DESC LIMIT " . $start . "," . $c . " ") or die(mysql_error());

But I get the error message:Incorrect parameter count in the call to native function 'IsNull'

Anybody have any ideas? I'm pretty new to mySQL.

Answer 1

You might consider using coalesce: http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html#function_coalesce

It returns the first non-null value.

Answer 2

ISNULL tests if the passed expression is NULL. What you need is IFNULL, or COALESCE, as xyld has mentioned.

SELECT crawled.id, IFNULL(sranking.score, 0) as Score, ...