Duplicate entries in PHP&MySQL

[pblack]

Is there a way of avoiding duplicate entries in a database using PHP & MySQL.

[lozza1978]

mysql will store any data you enter.

If you want to have a unique database, then you will have to query the server for the unique data before you issue an update

i think you could use

mysql_num_rows();
to query the server, if this returns more than 0 then the data is already in the database, and this data is duplicate,

HTH

[thorpe]

or you could just create a UNIQUE constraint on the filed you want to maintain unique values in. example;

CREATE TABLE users (
username VARCHAR(80) UNIQUE
);

this way, if anyone tries to enter a username that already exists an error would be generated and the query would fail.

[Sxooter]

The best way I've found is to create every form with something like an md5 sum in it from the current time, then insert that into a unique field upon posting. That way, if someone hits refresh right after posting, the same md5 shows up and produces an error on the unique violation.