if user exists

chrisleon

I need to know how to check if a user is in the database before I add him/her. Is there any validating code that I could use?

please help

thanx

cgraz

$query = mysql_query("SELECT * FROM your_table WHERE user=jason");

$num_rows = mysql_num_rows($query);

if ($num_rows == '0') {
    // username does not already exist in db
} else {
    // username already exists in db
}

Cgraz

nemonoman

HERE are 3 basic approaches:

INSERT into mytable (name) VALUES ('Nemo')

SELECT the information you're about to INSERT.

SELECT * FROM mytable WHERE name='Nemo'

Then if mysql_num_rows>0, don't do the insert.

Always provisionally DELETE, then do the insert.

DELETE FROM mytable WHERE name='Nemo';

INSERT into mytable (name) VALUES ('Nemo')

Set the column in question as UNIQUE, do the insert, and if the insert fails don't sweat it, just inform the user of a duplicate value.

[deleted]

"HERE are 3 basic approaches: "

Yup, two wrong ones and the correct one, which luckily you also mention:

" 3. Set the column in question as UNIQUE, do the insert, and if the insert fails don't sweat it, just inform the user of a duplicate value."

Every other method is un-acceptable because they do not guarantee uniqueness unless you put an exclusive lock on the table during the entire operation, and an exclusive lock is un-acceptable in a production environment (much too slow)

chrisleon

thank you very much, it worked perfect