test mysql query for no results

[nathanpacker]

Hey, I'm running a mysql query, and would like to run a script if the query returns no results. But what do I use to test for no results?

Something like:

[PHP]

if (!$query) {

do this

}

[/PHP]

But just not sure how to implement it. Little help?

[php_daemon]

if(mysql_num_rows($result)==0){
  //do this
}

[nathanpacker]

if(mysql_num_rows($result)==0){
  //do this
}

Thanks, that was perfect.

[1supergirl]

if(mysql_num_rows($result)==0){
  //do this
}

OMG, you helped me so much!! I am new to php, and I was tearing my hair out. Thank you, Thankyou,! You are my hero!!!!! :)

[jamesmjr]

Will this work for odbc_num_rows also. I tried but I get the same message no matter what

$sql="SELECT * FROM rac_master WHERE mrnumb='$mrnumb' AND racnumb='$racnumb' AND findetdate IS NULL";
   $resultx=odbc_exec($conna,$sql);
       if (odbc_num_rows($resultx)==0) {
           echo"Record Has Been Finalized";
           }
           odbc_close($conna);

[nathanpacker]

Can't say for sure, but one way to find out would just be to test it. Echo that variable out and see what you get.

[jamesmjr]

It returns "Record Has Been Finalized", even if the query statement is met. Does it matter what data type is being used in the table

[nathanpacker]

It returns "Record Has Been Finalized", even if the query statement is met. Does it matter what data type is being used in the table

Wish I could help you here. I'm a novice at this stuff. Maybe someone more experienced will chime in.

[jamesmjr]

Turns out the odbc_num_rows will always return -1 when using MSSQL. I changed my connecton to mssql_connect and mssql_num_rows . Every thing is working fine now.

Example:

$conn=mssql_connect('localhost','******','******');
 $msdb=mssql_select_db("DatabaseName",$conn);
 $sql="SELECT * FROM Table WHERE value='$variable' ";
 $result=mssql_query($sql,$conn);
         IF (mssql_num_rows($result)==0)  {
           echo"What ever";
           }
           mssql_close($conn);

[c++learner]

I was struggling with checking my empty results set before I loop with a while block until I found the above num_rows code and it worked right off. I think I spent 3 hours on this...amazing! Now I need to redirect back to the login page but this too is a struggle because I am using php header location and it's hard because I read that you are supposed to call before anything else. I'll get it though.

Thanks everyone!!!

[BradChesney79]

$query = "SELECT * FROM table";
$results = mysql_query($query);
if($results) {
  //do something
}
else {
  //do something different
}

mysql_query will return false if no records are returned. That false will be propagated into your variable. You can test for that. Try to use a smaller, quicker query; you don't want to tie up too many system resources if you don't end up needing the results of the query.

BradChesney79

[pritaeas]

mysql_query will return false if no records are returned.

This is incorrect. mysql_query will return true (or a resource) if the query succeeds. Even if there are no results, the query is still successful.

If mysql_query returns false , then the query is incorrect (or the user does not have permission).

[BradChesney79]

$query = "SELECT * FROM table"; 
$results = mysql_query($query);
if ($results) { // query executed
  $row=mysql_fetch_array($results) { // get an initial row array
    if($row) { // query returned at least one row
      do {
        // the existence of $row is true, do something
      } while ($row=mysql_fetch_array($results));
    }
    else {
      // the existence of $row is false, do something different
      // this is where you can put some code if your successful query returned 0 rows
    }
  }
  else {
    // query failed
    // I choose to send myself the error information
    // I try to provide some non-specific feedback to the user explaining a failure
  }
}

The row is where you can get a false when it is empty.

I recently needed to test for this and wanted to see if there was a more elegant way to accomplish the end result I was looking for. In a way, it did allow me to make my php more robust, but it did not allow me to reduce the lines of code.