mysql 对 表里的 两个属性去重

1.要去重的临时表：

   SELECT

    tpc.id courseId,tpc.name couresName

    FROM ( SELECT  * FROM ez_user_transaction_history euth WHERE euth.order_type = '3' ) uth

    LEFT JOIN `ez_train_practical_course_user` tpcu  ON tpcu.id = uth.order_id

    LEFT JOIN `ez_train_practical_course` tpc ON tpcu.practical_course_id = tpc.id

    LEFT JOIN `ez_user` u ON tpcu.user_id = u.id

    // 对表的 两个属性去重

    

    SELECT DISTINCT test.courseId ,couresName FROM

    (

    SELECT

    tpc.id courseId,tpc.name couresName

    FROM ( SELECT  * FROM ez_user_transaction_history euth WHERE euth.order_type = '3' ) uth

    LEFT JOIN `ez_train_practical_course_user` tpcu  ON tpcu.id = uth.order_id

    LEFT JOIN `ez_train_practical_course` tpc ON tpcu.practical_course_id = tpc.id

    LEFT JOIN `ez_user` u ON tpcu.user_id = u.id

    ) test