传递 Select 查询的列名以从临时 table 中检索

Question

我有一个临时 table，其中包含我想从特定 table (table A) 中检索的列名。

示例代码如下：

Declare @temp table (ColumnNames varchar(30))

insert into @temp 
values('Name'), ('Class'), ('School')

--select Query to retrieve only name,class and School columns
end

此处tableA包含超过10列

Answer 1

DECLARE @SQLTOEXECUTE VARCHAR(MAX),
           @Col VARCHAR(200)

DECLARE CURSOR curs FOR 
SELECT ColumnNames FROM @temp

SET @SQLTOEXECUTE = 'SELECT '

OPEN curs
FETCH NEXT FROM Curs
INTO @Col

WHILE @@FETCH_STATUS = 0 
BEGIN
   SET @SQLTOEXECUTE = @SQLTOEXECUTE + @Col + ', '

   FETCH NEXT FROM Curs
   INTO @Col
END

CLOSE curs
DEALLOCATE curs

SET @SQLTOEXECUTE = ' FROM <Table name goes here>' 
PRINT @SQLTOEXECUTE

这应该会让你继续前进

Answer 2

以下代码可以满足您的要求：

Declare @temp table (ColumnNames varchar(30))

insert into @temp 
values('Id'), ('Name')

DECLARE @ColumnNames nvarchar(max)

SELECT @ColumnNames = stuff((SELECT ',' + ColumnNames 
FROM @temp
FOR XML PATH('')), 1,1, '')

EXEC (N'SELECT ' + @ColumnNames + N' FROM TheTable')

但这从根本上是错误的。为什么你需要将列名存储在 table 变量中，然后读取它来构建 sql 语句？

传递 Select 查询的列名以从临时 table 中检索

Pass Column names for a Select Query to retrieve from temporary table

sql

sql-server

sql-server-2008-r2