Question

Col1        Col2        Col3        Col4    Col5        Col6    Col7    Col8
CH-0000001  IN-0000001  IN-0000001  ALL     NULL        NULL    NULL    NULL
CH-0000001  PR-0000001  NULL        NULL    PR-0000001  ALL     NULL    NULL
CH-0000001  PU-0000001  NULL        NULL    NULL        NULL    PU-0000001  ALL

嘿伙计们我试图根据密钥Col1将所有这些信息压缩成一行。我看过一个使用MAX和SUM的技巧，但它似乎只适用于数字。这是期望的结果。

Col1        Col3        Col4    Col5        Col6    Col7         Col8
CH-0000001  IN-0000001  ALL     PR-0000001  ALL     PU-0000001   ALL

此外，这个问题来自LEFT JOIN来自一个主密钥表的3个表。如果我达到这种状态的方法是解决这个问题的错误方法，请告诉我。这是查询

SELECT * FROM GCL_Blackboard A
LEFT JOIN GCL_Investors B ON A.Adjective_ID = B.Investor_ID
LEFT JOIN GCL_Loan_Programs C ON A.Adjective_ID = C.Program_ID
LEFT JOIN GCL_Loan_Purposes D ON A.Adjective_ID = D.Purpose_ID

Answer 1

我认为这是你想要的逻辑：

SELECT a.col1,
       max(coalesce(b.col2, c.col2, d.col2)) as col2,
       max(coalesce(b.col3, c.col3, d.col3)) as col3,
       max(coalesce(b.col4, c.col4, d.col4)) as col4,
       max(coalesce(b.col5, c.col5, d.col5)) as col5,
       max(coalesce(b.col6, c.col6, d.col6)) as col6,
       max(coalesce(b.col7, c.col7, d.col7)) as col7,
       max(coalesce(b.col8, c.col8, d.col8)) as col8
FROM GCL_Blackboard A LEFT JOIN
     GCL_Investors B
     ON A.Adjective_ID = B.Investor_ID LEFT JOIN
     GCL_Loan_Programs C
     ON A.Adjective_ID = C.Program_ID LEFT JOIN
     GCL_Loan_Purposes D
     ON A.Adjective_ID = D.Purpose_ID
GROUP BY a.col1;

查询有点猜测，因为我不知道列的来源。

Answer 2

你可以这样做：

SELECT A.Col1,
       MIN(Col3) Col3,
       MIN(Col4) Col4 ....
FROM GCL_Blackboard A
LEFT JOIN GCL_Investors B ON A.Adjective_ID = B.Investor_ID
LEFT JOIN GCL_Loan_Programs C ON A.Adjective_ID = C.Program_ID
LEFT JOIN GCL_Loan_Purposes D ON A.Adjective_ID = D.Purpose_ID
GROUP BY A.Col1

将多个varchar行合并为一个

2 个答案: