Question

这是我的代码：

drop table if exists #Table_A
drop table if exists #Table_B
drop table if exists #Table_C

create table #Table_A
(
    [DATE] Date,
    TYPE    INT,
    QTY     INT
);

create table #Table_B
(
    [DATE] Date,
    TYPE    INT,
    QTY     INT
);

create table #Table_C
(
    [DATE] Date,
    TYPE    INT,
    QTY     INT
);

Insert into #Table_A VALUES ('2018-01-01', 1, 10)
Insert into #Table_B VALUES ('2018-01-01', 1, 5)
Insert into #Table_B VALUES ('2018-01-01', 2, 10)
Insert into #Table_B VALUES ('2018-01-01', 3, 10)
Insert into #Table_C VALUES ('2018-01-01', 1, 5)
Insert into #Table_C VALUES ('2018-01-01', 2, 10)
Insert into #Table_C VALUES ('2018-01-01', 3, 10)

查询：

select 
    A.[DATE], 
    SUM(CASE WHEN A.[TYPE] = 1 THEN A.QTY END)  A_QTY,
    SUM(CASE WHEN B.[TYPE] = 1 THEN B.QTY END)  B_QTY,
    SUM(CASE WHEN C.[TYPE] = 1 THEN C.QTY END)  C_QTY,
    SUM(CASE WHEN A.[TYPE] = 2 THEN A.QTY END)  A_QTY,
    SUM(CASE WHEN B.[TYPE] = 2 THEN B.QTY END)  B_QTY,
    SUM(CASE WHEN C.[TYPE] = 2 THEN C.QTY END)  C_QTY,
    SUM(CASE WHEN A.[TYPE] = 3 THEN A.QTY END)  A_QTY,
    SUM(CASE WHEN B.[TYPE] = 3 THEN B.QTY END)  B_QTY,
    SUM(CASE WHEN C.[TYPE] = 3 THEN C.QTY END)  C_QTY
FROM 
    #Table_A A 
    INNER JOIN #Table_B B ON A.DATE = B.DATE AND A.TYPE = B.TYPE
    INNER JOIN #Table_C C ON A.DATE = C.DATE AND A.TYPE = C.TYPE
GROUP BY A.[DATE]

当前结果：

DATE        |   A_QTY   |   B_QTY   |   C_QTY   A_QTY   B_QTY   C_QTY   A_QTY   B_QTY   C_QTY
2018-01-01  |   10      |   5       |   5       NULL    NULL    NULL    NULL    NULL    NULL

预期结果：

DATE        |   A_QTY   |   B_QTY   |   C_QTY   A_QTY   B_QTY   C_QTY   A_QTY   B_QTY   C_QTY    
2018-01-01  |   10      |   5       |   5       NULL    10      10      NULL    10      10

请让我知道如何获得预期的结果。（我知道当前由于inner join而无法正常工作。）

Answer 1

查询的问题在于，由于它使用INNER JOIN，因此仅计算所有3个表中都存在的记录/日期元组。

如果存在一个表，该表可以始终始终具有所有（TYPE，DATE）元组（在示例数据中，则为Table_C ），那么您可以将其用作起点并使用LEFT JOIN s：

FROM #Table_C C 
LEFT JOIN #Table_A A ON A.DATE = C.DATE AND A.TYPE = C.TYPE
LEFT JOIN #Table_B B ON B.DATE = C.DATE AND B.TYPE = C.TYPE

否则，您可能希望将INNER JOIN更改为FULL OUTER JOIN s：

FROM #Table_A A 
FULL OUTER JOIN #Table_B B ON A.DATE = B.DATE AND A.TYPE = B.TYPE
FULL OUTER JOIN #Table_C C ON A.DATE = C.DATE AND A.TYPE = C.TYPE

FULL OUTER JOIN解决方案需要修改SELECT和GROUP BY子句，因为日期可能来自3个表中的任何一个。

查询：

SELECT
    COALESCE(A.[DATE], B.[DATE], C.[DATE]) DATE,
    SUM(CASE WHEN A.[TYPE] = 1 THEN A.QTY END)  A_QTY,
    SUM(CASE WHEN B.[TYPE] = 1 THEN B.QTY END)  B_QTY,
    SUM(CASE WHEN C.[TYPE] = 1 THEN C.QTY END)  C_QTY,
    SUM(CASE WHEN A.[TYPE] = 2 THEN A.QTY END)  A_QTY,
    SUM(CASE WHEN B.[TYPE] = 2 THEN B.QTY END)  B_QTY,
    SUM(CASE WHEN C.[TYPE] = 2 THEN C.QTY END)  C_QTY,
    SUM(CASE WHEN A.[TYPE] = 3 THEN A.QTY END)  A_QTY,
    SUM(CASE WHEN B.[TYPE] = 3 THEN B.QTY END)  B_QTY,
    SUM(CASE WHEN C.[TYPE] = 3 THEN C.QTY END)  C_QTY
FROM 
    #Table_A A 
    FULL OUTER JOIN #Table_B B ON A.DATE = B.DATE AND A.TYPE = B.TYPE
    FULL OUTER JOIN #Table_C C ON A.DATE = C.DATE AND A.TYPE = C.TYPE
GROUP BY COALESCE(A.[DATE], B.[DATE], C.[DATE])

此 demo on DB Fiddle 返回：

DATE                | A_QTY | B_QTY | C_QTY | A_QTY | B_QTY | C_QTY | A_QTY | B_QTY | C_QTY
:------------------ | ----: | ----: | ----: | ----: | ----: | ----: | ----: | ----: | ----:
01/01/2018 00:00:00 |    10 |     5 |     5 |       |    10 |    10 |       |    10 |    10

T-SQL结果集-具有3个表

1 个答案: