preventing duplicate row insertion in php/mysql

Question

how do you prevent the entry of duplicate records in php mysql? validating input before insertion to the table. i am currently building a user registration section for my website but want to present them with an error if a duplicate username or email address is found in the database. EDIT This is what I have to far to insert rows... how would I implement both these answers here: ``` ".$Cuser." (".$Cemail.") has been successfully added to the database.

Return"; exit; } ?> ``` I'm guessing that I could implement it all in an if...else statement?

Accepted Answer

i used the sql statement along with an if else statement.

```
mysql_select_db($database_speedycms, $speedycms);
$query_usercheck = "SELECT * FROM tbl_users WHERE username='$user' OR email='$email'";
$usercheck = mysql_query($query_usercheck, $speedycms) or die(mysql_error());
$row_usercheck = mysql_fetch_assoc($usercheck);
$totalRows_usercheck = mysql_num_rows($usercheck);
```

then

```
if ( $totalRows_usercheck > 0 )
```

display an error message to prevent any duplicates from being added

otherwise allow database insert

preventing duplicate row insertion in php/mysql

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