mysql利用创建临时表方法去除数据表中重复值

查了很多mysql数据表去重的资料，还是创建临时表的方法靠谱

//去重

    $sql1 = "CREATE TEMPORARY TABLE tmp_table SELECT * FROM tablename group by `name`";
    $pdo1->exec($sql1);
    $sql2 = "drop  TABLE tablename;
    $pdo1->exec($sql2);
    $sql3 = "CREATE  TABLE tablename SELECT * FROM tmp_table";

    $pdo1->exec($sql3);

DROP TEMPORARY TABLE tmp_table

//查重复数据

select user_name,count(*) as count from user_table group by user_name having count>1;