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@NogDogJun 23.2006 — #@NogDogJun 23.2006 — #
Not quite: the second test is telling you the query failed to process, not that it was successful but no rows were returned. In other words, if the mysql_num_rows() returns 0, that's telling you that the query was properly formed and processed, but no data was found in the DB that matched it; whereas if the result of your mysql_query() is false, then your SQL was incorrect, or the database connection was down, or some other error not related to whether or not there was matching data in the database.
code to determine query returned no record
Hi
I’m trying to use the expression:
if (mysql_num_rows($qry) > 0)
to test whether a record exists with certain criteria. I get the error “mysql_num_rows(): supplied argument is not a valid MySQL result resource” – I assume because $qry doesn’t return anything. What’s the right way to do this test?
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@NogDogJun 23.2006 — #[code=php]
$result = mysql_query($query);
if($result) // query did not fail outright
{
if(mysql_num_rows($result))
{
// we got at least 1 result row
}
else
{
// no matches found in DB
}
}
else
{
// query failed (such as due to SQL syntax error)
// might want to echo a mysql_error() here for debugging purposes
}
[/code]0
@NogDogJun 23.2006 — #Thanks Nog, that's where I was headed.
In my tests, if
(!mysql_num_rows($result)) // 0 rows
then
(!$result) // query failed
so in my tests, the second test is unnecessary.
Anyway, much obliged.[/QUOTE]
Not quite: the second test is telling you the query failed to process, not that it was successful but no rows were returned. In other words, if the mysql_num_rows() returns 0, that's telling you that the query was properly formed and processed, but no data was found in the DB that matched it; whereas if the result of your mysql_query() is false, then your SQL was incorrect, or the database connection was down, or some other error not related to whether or not there was matching data in the database.