Question

我正在试图找出如何执行JOIN，其中我返回a.ssan = c.ssn下面的结果集（查询1）中的所有记录：

查询1：

SELECT 
a.memno, 
a.name, 
a.addr1, 
a.addr2, 
a.city, 
a.state, 
a.zip, 
a.sex, 
a.lname, 
a.ssan, 
b.addr1 as old_addr1, 
b.addr2 as old_addr2, 
b.city as old_city, 
b.state as old_state, 
b.zip as old_zip, 
b.timec 

FROM Lib1.Table1 a, Lib1.Table2 b 

WHERE 
a.memno = b.memno and 
b.groupid = 'P2' and 
b.type = 'B' and 
b.datec = 20131206 AND 
(a.addr1 <> b.addr1 or 
a.addr2 <> b.addr2 or 
a.city <> b.city or 
a. state <> b.state or 
a.zip <> b.zip)

表C字段：

SSN
DATEC
TIMEC
PRINT_OLD
PRINT_NEW

我正在为NEW和OLD地址生成邮件合并文档，以提醒成员他们帐户上的地址更改。制作新地址信件时，我在TABLEC上运行插入，设置除PRINT_OLD以外的所有字段的值。示例数据将是：

SSN: 123456789; 
DATEC: 20131206; 
TIMEC: 133000; 
PRINT_NEW: 2013-12-06-13.30.00.965000; 
PRINT_OLD: NULL;

然后几天后，当打印旧地址字母时，我需要在T JOIN上运行上面的第一个查询和TABLEC，以显示PRINT_OLD字段 NULL 的那些记录，表示已经打印了新的地址信那天，但旧地址信没有。

任何人都可以帮我解决这个问题吗？在数据库查询方面，我不是最强的。

Answer 1

你可以这样做：

SELECT *
FROM tableC c
INNER JOIN (
  SELECT a.memno,
    a.NAME,
    a.addr1,
    a.addr2,
    a.city,
    a.STATE,
    a.zip,
    a.sex,
    a.lname,
    a.ssan,
    b.addr1 AS old_addr1,
    b.addr2 AS old_addr2,
    b.city AS old_city,
    b.STATE AS old_state,
    b.zip AS old_zip,
    b.timec
  FROM Lib1.Table1 a
  INNER JOIN Lib1.Table2 b ON a.memno = b.memno
  WHERE b.groupid = 'P2'
    AND b.type = 'B' AND b.datec = 20131206
    AND (
      a.addr1 <> b.addr1 OR a.addr2 <> b.addr2
      OR a.city <> b.city OR a.STATE <> b.STATE
      OR a.zip <> b.zip)
  ) a ON a.ssan = c.ssn
WHERE c.print_old IS NULL

注意：我还将您的JOIN更改为显式的INNER JOIN。

Answer 2

由于您引用了Lib1和Lib2，我假设您使用的是IBM中端系统，对吗？

我认为memno在table1中是唯一的，{memno，groupid，type，datec}在tableb中是唯一的。

 SELECT a.memno, 
        a.name, 
        a.addr1, 
        a.addr2, 
        a.city, 
        a.state, 
        a.zip, 
        a.sex, 
        a.lname, 
        a.ssan, 
        b.addr1 as old_addr1, 
        b.addr2 as old_addr2, 
        b.city as old_city, 
        b.state as old_state, 
        b.zip as old_zip,
        b.datec, 
        b.timec, 
        c.PRINT_OLD
        c.PRINT_NEW
   FROM Lib1.Table1 a
   JOIN Lib1.Table2 b   
           ON a.memno = b.memno
          and b.datec = 20131206
          AND (a.addr1, a.addr2, a.city, a.state, a.zip)
           <> (b.addr1, b.addr2, b.city, b.state, b.zip)
   JOIN Lib1.TableC c
           ON c.ssn = a.ssan
          and c.datec = b.datec
          and c.timec = b.timec
   WHERE c.PRINT_OLD is NULL                   
     and b.groupid = 'P2' 
     and b.type = 'B'
     and b.datec = 20131206

我怀疑这与你正在寻找的更接近，并展示了一些不同的技巧。

如何加入我的结果集和第三个表？

2 个答案: