Question

表：

CREATE TABLE Figure(
MonthNumber varchar(10),
Code varchar(10),
Figure int
);

INSERT INTO Figure (MonthNumber, Code, Figure)
VALUES ('5', 'S', '25'),
('5','G', '30'),
('4','K', '30');

CREATE TABLE Person(
Code varchar(10)
);

INSERT INTO Person (Code)
VALUES ('S'),
('G' ),
('K' ),
('D' ),
('J');

查询：

SELECT F.[MonthNumber],
f.[Code],
f.[Figure]
FROM 
Figure F
RIGHT JOIN Person P
ON F.[Code] = P.[Code]

WHERE F.[MonthNumber] = '5'

结果：

| MonthNumber | Code | Figure |
|-------------|------|--------|
|           5 |    S |     25 |
|           5 |    G |     30 |

但我正在寻找这样的结果：

| MonthNumber | Code | Figure |
|-------------|------|--------|
|           5 |    S |     25 |
|           5 |    G |     30 |
|           5 |    K |     30 |
|           5 |    D |      0 |
|           5 |    J |      0 |

我想将这些数字限制在第5个月，但即使他们没有数字，也会把所有人带回来。我认为使用正确的连接语法对此是正确的，但它没有给我我想要的结果。我无法真正理解我需要的逻辑。任何帮助表示赞赏。感谢

Answer 1

外部联接似乎正确。为什么使用RIGHT JOIN代替LEFT JOIN？后者通常更容易遵循。

SELECT '5' as MonthNumber, p.[Code], COALESCE(f.Figure, 0) as Figure
FROM Person P LEFT JOIN
     Figure F
     ON F.[Code] = P.[Code] AND F.MonthNumber = '5';

第二个表（在LEFT JOIN中）的条件需要进入ON子句。

Answer 2

我认为这会做它应该做的事情，但不会因为数据而完全提出要求：

SELECT F.[MonthNumber], -- this wont select 5 for all rows, but you can hard code this to the 5
P.[Code],
ISNULL(f.[Figure], 0) AS Figure
FROM 
Person P 
LEFT OUTER JOIN Figure F ON P.[Code] = F.[Code]
    AND F.[MonthNumber] = '5'

Answer 3

您可以使用下面的查询。

更新小提琴 - http://sqlfiddle.com/#!18/6552d/24

SELECT 
MonthNumber= ISNULL(MonthNumber,'5'),
P.Code,
Figure= ISNULL(Figure,0)
FROM 
Figure F
RIGHT JOIN Person P
ON F.[Code] = P.[Code]
AND F.[MonthNumber] ='5'

Answer 4

Try this I hope it helps

CREATE TABLE #Figure(
MonthNumber varchar(10),
Code varchar(10),
Figure int
);

INSERT INTO #Figure (MonthNumber, Code, Figure)
VALUES ('5', 'S', '25'),
('5','G', '30'),
('4','K', '30');

CREATE TABLE #Person(
Code varchar(10)
);

INSERT INTO #Person (Code)
VALUES ('S'),
('G' ),
('K' ),
('D' ),
('J');



SELECT F.[MonthNumber],
P.[Code],
f.[Figure]
FROM #Person  p
LEFT  JOIN #Figure F
ON P.[Code] = F.[Code]

WHERE F.[MonthNumber] = '5' 
or F.[MonthNumber] is null

Join子句从两个表SQL Server返回结果

4 个答案: