check whether value exists in a table column?

[biscutty]

As a newb, this probably will sound real easy...

How do I check whether a record from a variable exists in a column of a table named "customers".

IF False then run a bit of code... otherwise bypass this bit of code and continue the script.

The connection to the database has been made and the table selected..

Also - to do with the table design? the record I am checking for is a string and not indexed, will performance become an issue as records are added to the column and the script needs to serch through a few thousand records to find if the record it is looking for exists?

$sql = " SQL QUERY I NEED HELP WITH";

   if (mysql_query($sql)) { Do something }

Thanks for any helps!

Biscutty

[treds1]

$result=mysql_query("SELECT * FROM customers WHERE column_name='$variable'");

if(num_rows($result)>0)
{
do this

}
else
{
do this

}

you may need to change statement slightly depending upon how you connect to db but sql between "" should be fine

[Sxooter]

Note that if you're doing this to prevent duplicate entries, then you shoudl go ahead and add a unique index to the table as well to ensure that race conditions don't bite you later on.

[Kaine]

if you want to check a value exists within the SQL query you can use a query like:

EXISTS (SELECT * FROM CUSTOMER WHERE NAME = "Fred")

-K-