Question

我有2张桌子

具有3列的表A：ID, NAME, VALUE 1
具有3列的表B：ID, NAME, VALUE 2

表A：编号：A1，A2 名称：AAA，BBB 值1：1000,2000

表B：编号：B1，B2 名称：CCC，DDD 值1：3000,4000

我想显示这样的结果：

ID，NAME，VALUE 1，VALUE 2 A1 AAA 1000 A2 BBB 2000 A3 CCC 3000 A4 DDD 4000

我尝试了union，它适用于id, name列。普通的select + union select可以吗？

Answer 1

您可以使用union all：

select id, name, value1, null as value2
from a
union all
select id, name, null as value1, value2
from b;

Answer 2

您也可以使用Full Outer Join

SELECT a.id, a.name, a.value1, b.value2
FROM tableA as a
FULL OUTER JOIN tableB AS b ON
a.id = b.id

Answer 3

online demonstration

MS SQL Server 2017架构设置：

CREATE TABLE Table1
    ([ID] varchar(2), [NAME] varchar(3), [VALUE1] int)
;

INSERT INTO Table1
    ([ID], [NAME], [VALUE1])
VALUES
    ('A1', 'AAA', 1000),
    ('A2', 'BBB', 2000)
;


CREATE TABLE Table2
    ([ID] varchar(2), [NAME] varchar(3), [VALUE2] int)
;

INSERT INTO Table2
    ([ID], [NAME], [VALUE2])
VALUES
    ('B1', 'CCC', 3000),
    ('B2', 'DDD', 4000)
;

查询1 ：

select id, name, value1, null as value2
from table1
union all
select id, name, null as value1, value2
from table2

Results ：

| id | name | value1 | value2 |
|----|------|--------|--------|
| A1 |  AAA |   1000 | (null) |
| A2 |  BBB |   2000 | (null) |
| B1 |  CCC | (null) |   3000 |
| B2 |  DDD | (null) |   4000 |

在SQL Server中组合select和select union

3 个答案: