ITEEDU

3.7.2. 显示孪生对状态的表

每一次会面以一个称为event的状态码结束。下面显示的查询被用来显示按事件组合的所有孪生的表。这表明多少对孪生已经完成，多少对的其中之一已完成而另一个拒绝了，等等。

SELECT
        t1.event,
        t2.event,
        COUNT(*)
FROM
        lentus AS t1,
        lentus AS t2,
        twin_project AS tp
WHERE
        /* We are looking at one pair at a time */
        t1.id = tp.id
        AND t1.tvab=tp.tvab
        AND t1.id = t2.id
        /* Just the screening survey */
        AND tp.survey_no = 5
        /* This makes each pair only appear once */
        AND t1.tvab='1' AND t2.tvab='2'
GROUP BY
        t1.event, t2.event;