Question

我有两张表A和表B

一个。

channelname  variablename
------------------------------
TCO1           INPUT CHANNEL  
TC02           OUTPUT CHANNEL
TCO3           TEST CHANNEL

B中。

TC01    TC02   TC03
--------------------
100     443    322
200     566    990
376     453    342
45      422    856

我希望表B的输出为：

inputchannel   outputchannel   testchannel
--------------------------------------------- 
100            443             322
200            566             990
376            453             342
45             422             856

Answer 1

如果您不想更改列名，则需要使用游标：类似的东西：

    Declare @sSQL as varchar(400) -- You can alway make it larger
    Declare @channelname  as varchar(50) -- You can alway make it larger
    Declare @variablename  as varchar(50) -- You can alway make it larger
    Set @sSQL=''
    DECLARE col_cursor CURSOR FOR 
    select c.name, a.variablename from 
    sys.columns c 
    inner join sys.tables t on c.object_id = t.object_id 
    inner join [A] as a on a.channelname = c.name 
    where t.name = 'B'
    OPEN col_cursor
    FETCH NEXT FROM col_cursor 
    INTO @channelname, @variablename
    WHILE @@FETCH_STATUS = 0
    BEGIN
        If @sSQL=''
        BEGIN
            Set @sSQL='select [' + @channelname + ']as[' + @variablename + '] '
        END
        ELSE
        BEGIN
            Set @sSQL= @sSQL + ',[' + @channelname + ']as[' + @variablename + '] '
        END
        FETCH NEXT FROM col_cursor 
        INTO @channelname, @variablename
    END 
    CLOSE col_cursor
    DEALLOCATE col_cursor
    Set @sSQL= @sSQL + ' from [B]'
    Exec(@sSQL)

Answer 2

因为人们不喜欢游标：

declare @var nvarchar(max) = N'create table ##temp ('
select @var = @var + variablename + ' varchar(max),' from TableA
set @var = LEFT(@var, LEN(@var) - 1) + ')'

execute sp_executesql @var

insert into ##temp
select * from TableB

select * into TableNew from ##temp
drop table TableB

编辑当然在删除任何表之前对此进行测试。

Answer 3

根据评论：

我想创建一个查询来重命名所有列。 - 奥森 DCunha

请尝试这样的事情：

declare @columnNameFrom nvarchar(100), @columnNameTo nvarchar(100)
declare @tablename nvarchar(100)

SET @tablename  = 'B'

DECLARE rename_cursor CURSOR FOR 
    select @tablename + '.' + c.name
    ,      A.variablename
    from   syscolumns c 
           inner join sysobjects o on o.id = c.id
           inner join A on A.channelname = c.name
     where  o.name = @tablename  

OPEN rename_cursor 
FETCH NEXT FROM rename_cursor 
INTO @columnNameFrom, @columnNameTo
WHILE @@FETCH_STATUS = 0
BEGIN
  SET @columnNameTo = REPLACE(@columnNameTo, ' ', '')
  EXEC sp_executesql N'exec sp_rename @NameFrom, @NameTo'
  , N'@NameFrom nvarchar(100), @NameTo nvarchar(100)'
  , @columnNameFrom, @columnNameTo;

  FETCH NEXT FROM rename_cursor  
  INTO @columnNameFrom, @columnNameTo
END 
CLOSE rename_cursor 
DEALLOCATE rename_cursor ;

在sql中将行映射到列名

3 个答案: