comparing user input values in a form with database values

[rekhad]

Hi!
I want to compare user input values in a form with my database.
Basically I want to check whether the user exits in my database.
What mysql command can do that?

[jatar_k]

are your usernames unique? if so you can issue a select query and then test if mysql_num_rows > 0

select * from tablename where column='data'

you would obviously add your actual tablename and then the column you would like to select with and the data you have to use about your user

[rekhad]

Yes name are unique.
Is this what I need to do

$firstName=$_POST["first_name"];
$query=mysql_query(SELECT * FROM table1 WHERE first_name="$firstName");
$result=mysql_num_rows($query);

[jatar_k]

I highly doubt first name will remain unique, I was referring to username or maybe even email

but

$firstName=$_POST["first_name"];
$query=mysql_query(SELECT * FROM table1 WHERE first_name="$firstName");
$result=mysql_num_rows($query);

that would work and then you can do
if ($result < 1) {

would mean that there were no rows returned and you could carry on, though you might also want to do the opposite
if ($result > 0) {
this way you can error out right away if there is a row selected and return to the user or whatever you need to do

[rekhad]

How will it test whether the user exits or not?
will it go row by row and test it?

$query=mysql_query(SELECT * FROM table1 WHERE first_name=\"$firstName\"); is gving me parse error..

[rekhad]

ignore my last post it was a typo error