Question

这是我的sql架构：

Table 1: scan_1             Table 2: scan_2          Table 3: scan_detail

P_no        work            P_no        work           P_no       work_date
 1          YES              1          YES             1         2017/11/03
 2          YES              2          NO              2         2017/12/31
 3          NO               3          NO              3         2017/12/13

我想从scan_1和scan_2计算P_no，其中日期范围属于scan_detail。我使用此查询来计算scan_1和scan_2中的P_no，但无法在查询中添加scan_detail。

SELECT COUNT(*) AS pick FROM (SELECT P_no, work FROM scan_1 WHERE work = 'YES' UNION SELECT P_no, work FROM scan_2 WHERE work = 'YES') AS total

在上面的查询中，我想从scan_detail添加日期范围，如

  select count(P_no) from scan_detail where work_date >='2017/11/03' and work_date <= '2017/12/31'

Answer 1

您可以使用您的联合结果集扫描1＆amp; 2

SELECT 
  COUNT(*) AS pick 
FROM scan_detail d
JOIN (SELECT P_no,`work` FROM scan_1 WHERE `work` = 'YES' 
      UNION
      SELECT P_no,`work` FROM scan_2 WHERE `work` = 'YES'
  ) AS s  USING(P_no) 
WHERE d.work_date >='2017/11/03' AND d.work_date <= '2017/12/31'

Answer 2

使用连接查询添加日期时间，然后应用过滤器。伪查询在下面给出

SELECT COUNT(P_no) AS pick 
FROM (SELECT a.P_no as P_no, a.work as work, b.work_date work_date 
      FROM scan_1 
      LEFT JOIN scan_details b on (a.P_no = b.P_no) 
      WHERE work = 'YES' 
      UNION 
      SELECT c.P_no, c.work, d.work_date work_date 
      FROM scan_2 c 
      LEFT JOIN scan_details d on (c.P_no = d.P_no) 
      WHERE work = 'YES'     
      where work_date between date1 and date2)

如何使用sql在另一个表的帮助下从两个表中获取值

2 个答案: