Insert data only if record does not exist

Question

I want to insert data in a table only if the record with a given CatalogID does not exist.

 $userId = $_POST[\'userId\'];
 $catalogID = $_POST[\         


        

Answer 1

You could use this sort of function

public function Checkrecord($catalogID )
    {
        $query="Select * from table_name where catalog_id=$catalogID ";
                  mysql_query($query,$con);
        if(mysql_num_rows($query)>0)
        {
            //report error
        }
        else
        {
            //insertQuery
        }
    }

Answer 2

Create a UNIQUE index on CatalogID.

Answer 3

$query="INSERT INTO LibraryMaster (UserID,CatalogID,ContentAddedDateTime)
SELECT * FROM (SELECT '".$userId."', '".$catalogID."', '".$content_AddedTime."') AS tmp
WHERE NOT EXISTS (
  SELECT CatalogID FROM LibraryMaster WHERE CatalogID = '".$catalogID."t'
 ) LIMIT 1";