查询在列和 select 列名之间循环

Question

我想多次执行同一个查询，每次使用一个不同的列并打印列名。

换句话说，我想执行以下操作：

第一次查询

SELECT DISTINCT [Name],[C12],'C12' AS [Description]
FROM #MyTable

第二次查询

SELECT DISTINCT [Name],[C13],'C13' AS [Description]
FROM #MyTable

第三次查询

SELECT DISTINCT [Name],[C14],'C14' AS [Description]
FROM #MyTable

我现在所做的是以下代码：

DECLARE @Member AS VARCHAR(20)
DECLARE Csr cursor for SELECT 'C12' UNION SELECT 'C13' UNION SELECT 'C14'
OPEN Csr
    FETCH NEXT FROM Csr INTO @Member
    WHILE (@@fetch_status <> -1)

    BEGIN
        exec('SELECT DISTINCT [Name],'+@Member+', ''+@Member+'' AS [Description]
                    FROM #MyTable
            ')
        FETCH NEXT FROM Csr INTO @Member
    END
CLOSE Csr
DEALLOCATE Csr

接近预期的结果，但我得到的是 Description 列

+@Member+

而不是每次迭代分配给变量的值。

有人可以帮我吗？

Answer 1

不需要游标，动态即可轻松实现 SQL:

declare @query nvarchar(400) = ''
select @query = @query + ' select name,''' + name + ''',' + name + ' from #MyTable'  from tempdb.sys.columns
where object_id = (
    select object_id from tempdb.sys.tables
    where name like '#MyTable%'
) and name <> 'name'

execute sp_executesql @query

查询在列和 select 列名之间循环

Query that loop between columns and select the column name

sql-server

exec

cursor

while-loop

sql-server-2012