Fixing the error: mysql_num_rows(): supplied argument is not a valid MySQL result resource

Question

I'm not sure why this is not working:

if($strFilterByStatus != 'all' &&  $strFilterByYear == 'all' && $strFilterByMonth !='all')
{
    $strSQL = "SELECT * FROM tblcase where recovered = '".$strFilterByStatus."' and monthreported = '".$strFilterByMonth."'" ;
}
else if($strFilterByStatus != 'all' &&  $strFilterByYear != 'all' && $strFilterByMonth !='all')
{
    $strSQL = "SELECT * FROM tblcase where recovered = '".$strFilterByStatus."' and yearreported = '".$strFilterByYear."' and monthreported = '".$strFilterByMonth."'" ;
}


if (mysql_num_rows($strSQL)==0)
{
    $strCaseExist = false;
}
else
{
    $SQL=mysql_query($strSQL);  
    $strCaseExist = true;
}

I have 2 different SQL statements and I just want to know if it will return a record or not.

Please [don't use `mysql_*`](http://stackoverflow.com/questions/12859942/why-shouldnt-i-use-mysql-functions-in-php?rq=1); the `mysql_*` functions are outdated, [deprecated](http://us3.php.net/manual/en/intro.mysql.php), and insecure. Use [`MySQLi`](http://us3.php.net/manual/en/book.mysqli.php) or [`PDO`](http://us3.php.net/manual/en/intro.pdo.php) instead. — elixenide, Mar 08 '14 at 16:30
Because you're not executing the query, simply setting a string containing the query — Mark Baker, Mar 08 '14 at 16:31
ah yeah mark baker your right dammmmmmn so stupid not to see that thank you @ed cottrell thanks i will take it to consideration — Birdun, Mar 08 '14 at 16:33

score 2 · Accepted Answer · answered Mar 08 '14 at 16:33

2

You are not executing the query.check this manual for more details on mysql_num_rows() ,change your code like this

$resrce =mysql_query($strSQL)
if (mysql_num_rows($resrce)==0)

Beware about mysql functions, they are insecure and deprecated. Choose mysqli or pdo

answered Mar 08 '14 at 16:33

Sanoob

2,398
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1

yes correct thank you, been a while since i used php :) – Birdun Mar 08 '14 at 16:38

score 2 · Answer 2 · answered Mar 08 '14 at 16:33

2

mysql_num_rows requires a resultset to be passed not a string variable. Change to the following code:

$result = mysql_query( $strSQL );
$strCaseExist = (mysql_num_rows($result) == 0) ? false : true;

answered Mar 08 '14 at 16:33

hjpotter92

75,209
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score 1 · Answer 3 · answered Mar 08 '14 at 16:40

1

you have to execute the query BEFORE checking for num rows.

answered Mar 08 '14 at 16:40

JohnKochJR

133
10

Fixing the error: mysql_num_rows(): supplied argument is not a valid MySQL result resource

3 Answers3