php/mysql help

[uwannadonkey]

how can i check if a row EXISTS in my mysql table, through php.

 

for example, i wanna check if ID 6 exists in table, how would i do that.

[pocobueno1388]

<?php

$query = mysql_query("SELECT col FROM table WHERE ID=6")or die(mysql_error());

if (mysql_num_rows($query) > 0){
   //the row exists
} else {
   //doesn't exist
}

[awpti]

<?php

function row_exists($id)
{
   $res = mysql_query("SELECT * FROM my_table WHERE my_id_field = {$id}");
   if(mysql_num_rows($res) === 1)
   {
      return TRUE;
   }
   else
   {
      return FALSE;
   }
}

 

example;

<?php
if(row_exists($id))
{
    // it exists
}
else
{
    // it doesn't exist
}
?>

[pocobueno1388]

<?php

function row_exists($id)
{
   $res = mysql_query("SELECT * FROM my_table WHERE my_id_field = {$id}");
   if(mysql_num_rows($res) === 1)
   {
      return TRUE;
   }
   else
   {
      return FALSE;
   }
}

 

example;

<?php
if(row_exists($id))
{
    // it exists
}
else
{
    // it doesn't exist
}
?>

 

Thats a bit overkill, don't you think?

[uwannadonkey]

wow, thanks for your responses! ill test it out and get back to you all.

 

i prefer awpti's snippet, actually.

[awpti]

Thats a bit overkill, don't you think?

 

How many times is he going to use it?

 

If more than once; create a function.

 

Could even extend that function to allow variable table and field names.. oh, the magic of such functions goes on and on.

 

Code repetition is bad.

[Aureole]

Why are you selecting *... that is overkill... you only need to select one thing, e.g. the id...

 

EDIT: I don't think he was saying the function was overkill, he was saying SELECT * was overkill when a simple SELECT `id` or SELECT `column` would do.

 

[awpti]

Why are you selecting *... that is overkill... you only need to select one thing, e.g. the id...

 

 

Likely he's using MySQL and the MyISAM engine. "SELECT *" has the same performance as "SELECT field".

 

If it's innodb, that's different. Doubt it's innodb.

[Aureole]

How can selecting EVERYTHING from a table be quicker than/the same as selecting only one thing?

[awpti]

How can selecting EVERYTHING from a table be quicker than/the same as selecting only one thing?

 

It's just how the ISAM engine works. Do some performance benchmarks.

 

The only thing "SELECT *" does is give you a smidgen more data overhead.

[Aureole]

Well you probably know more than me, so I'll just take your word for it.