mysql查询，从3个表中选择

Question

我正在处理从 3 个表中提取唯一值的查询。这在 2 个单独的查询中完成更好吗？

查询是:

count as returned (
all leadID from lds where status = "ok"
AND leadID is also in rlds with recID="999"
AND rdate > (03-20-2012)
 + 
(all distinct leadID from plds where recID="999"
AND change != NULL
AND pdate > (03-20-2012)) 

工作查询的结果应该是“2”:leadID 1 和 leadID 4

表 lds:

领导ID |状态
1 |好的
2 |不好
3 |好的

表格:
线索编号 |记录 ID |改变 |更新
4 | 999 | CH1 | 03-27-2012
4 | 999 | CH2 | 03-27-2012
5 | 888|空 | 2012 年 3 月 27 日

表rlds:
线索编号 | recID2 |日期
1 | 999 | 03-27-2012
6 | 999 | 2012 年 3 月 27 日

谢谢!

Answer 1

SELECT Ids.leadId
FROM
    Ids JOIN
    rlds ON rlds.leadId = Ids.LeadId AND recID = 999 AND rdate > '03-20-2012'
WHERE Ids.Status = 'ok'

UNION

SELECT leadId
FROM pIds
WHERE recID = 999 AND change IS NOT NULL AND pdate > '03-20-2012'