help: checking before doing query in php with mysql

[don11]

Hello,

I have a problem. I run this query:

$query = "SELECT column1 FROM table WHERE column2='$kk'"; $which = $link1; 
mysql_query($query,$which);
some codes....

It is displaying all data correct but  only when $kk exists in column2 and when $kk does not exist, it display blank page.

So, i want to do a check before running above query to make sure that $kk exists in column2. How to check it before running query?

[trq]

You can't check without executing the query. The problem is likely that your not checking the results.

 

$query = "SELECT column1 FROM table WHERE column2='$kk'"; $which = $link1; 
if ($result = mysql_query($query)) {
  if (mysql_num_rows($result)) {
    // it is safe to use $result as it contains data
  } else {
    // no result where found
  }
} else {
  // query failed.
}

 

This is the basic syntax for ALL select queries.

[Muddy_Funster]

...

This is the basic syntax for ALL select queries.

That's a bit of a strong statement, perticularly with the capitalisation of ALL.  I dissagree, partly:

The first if is not, in my opinion, the best way of handeling an execution error - use of a try would, I think, be better.

Personal prefference on my part sees that I never nest variables within an SQL string, but break the string and add the variable with dot connectors.  Just because I have come across a fair few occasions whre people (myself included at the start) have tried to nest a variable within a single quoted string.

oh yeah....and I personaly have never build a query with "$which = $link1;" in it  .

 

Good template though - could be well worth starting a sticky with simple templates like this in it for a quick refference (though you may have to restrict posting in it to admins/mods so tubes like me don't ruin it )

 

 

[don11]

Checking the results after executing the query worked. Thanks alot phpfreaks staff helped me again. Thanks once again.