Question

我正在比较2个表。表1列1-5。表2列1-6。

如何在table1

中添加包含完整内容的第6列（来自table2）

Answer 1

以下是如何实现这一目标的示例：

DECLARE @FirstTable TABLE (
    FirstFirst VARCHAR(5),
    FirstSecond VARCHAR(5),
    FirstThird VARCHAR(5),
    FirstFourth VARCHAR(5),
    FirstFifth VARCHAR(5))
INSERT INTO @FirstTable
VALUES 
    ( '111', '121', '131', '141', '151' ),
    ( '112', '122', '132', '142', '152' ),
    ( '113', '123', '133', '143', '153' )

DECLARE @SecondTable TABLE (
    SecondFirst VARCHAR(5),
    SecondSecond VARCHAR(5),
    SecondThird VARCHAR(5),
    SecondFourth VARCHAR(5),
    SecondFifth VARCHAR(5),
    SecondSixth VARCHAR(5))
INSERT INTO @SecondTable
VALUES 
    ( '111', '121', '131', '141', '151', '161' ),
    ( '112', '122', '132', '142', '152', '162' ),
    ( '113', '123', '133', '143', '153', '163' )

--As a join
SELECT ft.*, st.SecondSixth FROM @FirstTable AS ft
LEFT JOIN @SecondTable AS st ON 
    ft.FirstFirst = st.SecondFirst AND
    ft.FirstSecond = st.SecondSecond AND
    ft.FirstThird = st.SecondThird AND
    ft.FirstFourth = st.SecondFourth AND
    ft.FirstFifth = st.SecondFifth

--As outer apply
SELECT ft.*, oa_secondTable.SecondSixth FROM @FirstTable AS ft
OUTER APPLY (
    SELECT TOP 1 st.SecondSixth FROM @SecondTable AS st
    WHERE 
        ft.FirstFirst = st.SecondFirst AND
        ft.FirstSecond = st.SecondSecond AND
        ft.FirstThird = st.SecondThird AND
        ft.FirstFourth = st.SecondFourth AND
        ft.FirstFifth = st.SecondFifth
) AS oa_secondTable

简短说明 - 两张桌子 - 第一个例子是与加入的比较 - 第二个例子是与外部申请比较

将表1中的列复制到表2并复制其内容

1 个答案: