php - 仅当记录不存在时才插入数据

Question

CatalogID仅当具有给定的记录不存在时，我才想在表中插入数据。

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

 $query = ("INSERT INTO LibraryMaster (UserID,CatalogID,ContentAddedDateTime)
      VALUES ('$userId','$catalogID','$content_AddedTime')");
 mysql_query($query,$con);
 printf("Records inserted: %d\n", mysql_affected_rows());
 echo($user_Name)

Answer 1

在 上创建UNIQUE索引CatalogID。

Answer 2

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

Answer 3

你可以使用这种功能

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
        }
    }