mysql_query gives Resource id #17

[KeredDrahcir]

Have a table that needs to have results written to it, that will later be updated. To check if the table has been written to yet I'm using this code:

    $sql="SELECT DISTINCT field FROM table WHERE field=".$value;
    $new_result=mysql_query($sql,$db);
    if (!$new_result)
    {
      do xyz      
    }

When I do this it doesn't enter the if. I tried echoing $new_results and got Resource id #17. What does this mean and what am I doing wrong that prevents me from entering the if. I tried the sql statement in an sql command prompt and it gave me Empty set (0.00 sec), which I was hoping for.

[code green]

From the manual

For SELECT, SHOW, DESCRIBE, EXPLAIN and other statements returning resultset, mysql_query() returns a resource on success, or FALSE on error

Does this clear things up?

[KeredDrahcir]

Not really. It's returning a Rescource on sucess but as I mentioned it was getting Empty Set (which I wanted) in the sql so surely it should be returning false?
Am I missing something?

[code green]

Yes, an empty result set is not an error.
To check for an empty result set use mysql_num_rows()

[KeredDrahcir]

Thanks. I did figure it out. I don't understand, that for some reason it did work to begin with and then now it suddenly stopped working.
I've got it woring now. I used mysql_get_row first and then checked it. Is mysql_num_rows a better function to use or are they both much the same?

[code green]

Entirely different.
mysql_get_row() Returns one row from the resultset.
It is generally used inside a loop to retrieve records.

mysql_num_rows() returns a count of the number of rows in the resultset.
It is generally used to check how many records the query found.

All this stuff is freely available in the PHP manual.
Download it and and use a link via your desktop for easy access

[KeredDrahcir]

Thanks. I know the difference between to functions. My code shows that I'm trying the check for a result. I was just wondering is using mysql_get_row() and then if (!$result) was better or worse than checking with mysql_num_rows()?

[code green]

Thanks. I know the difference between to functions

You may understand the functions but you are not using them the way nature intended.
By the way it is mysql_fetch_row not mysql_get_row().

mysql_get_row() and then if (!$result) was better or worse than checking with mysql_num_rows()?

mysql_fetch_row() takes the result resource as a parameter.
If there is no result resource it cannot return a row. So your suggestion is meaningless.
It is much better to use the right function for the right job in the right order.

if(false===($result = mysql_query($query,$resource))) error
if(mysql_num_rows($result)
{
 while($record = mysql_fetch_row($result))
}    

Or something like that.
I apologise for any syntax errors.

[KeredDrahcir]

I copied mysql_get_row() from your post.

$new_result_test=mysql_query($sql,$db);
$new_result = mysql_fetch_row($new_result_test);
if (!$new_result)
{
  new coffee();
}

This is what I have found to work. I was trying to find out if there was a better way of doing it. Am I doing something wrong there?

What I think I'm doing is running the query to try and get a row from the table. I'm doing that to check if a row with a specified value exists yet becuase if it doesn't I need to create it.
Is the method I've used stable?

[code green]

I think I understand what you are trying to achieve now.
If you simply want to know if a certain record exists, but you don't want to do anything with it,
the most efficient method would be

$sql="SELECT 1 FROM table WHERE field=".$value; //Will return first field only
$new_result_test = mysql_query($sql,$db); 
if(!mysql_num_rows($new_result_test); 
{ 
  new coffee(); 
} 
 

There is no need to return any rows from the resultset if you are not going to use them.
Remember mysql_query() will still return a resource if no rows are found so testing the resource only proves the query executed,
which is where I think you are getting confused.

[KeredDrahcir]

Thanks. If I do need to use the result, am I still better of testing mysql_num_rows or testing the result?

[code green]

Again, use the functions for the purpose intended.
There is no result to test, there is only the function return values

//mysql_query() returns a resource on success, or FALSE on error 
$result = mysql_query($query,$resource);
if($result != false)
{
if(mysql_num_rows($result) > 0) 
//returns a count of the number of rows in the resultset.
{
/*mysql_fetch_row() 
  Returns a numerical array that corresponds to the fetched row, 
  or FALSE if there are no more rows. */ 
 while($record = mysql_fetch_row($result)) 
}  
}