Question

我试图在另一个SQL查询中将SQL查询检索到的行用作列和表名

例如：

declare @var1 varchar(max)
declare @var2 varchar(max)
declare @result varchar(max)

set @var1 = 'cctl_country'
set @var2 = 'typecode'
set @result = 'select '+@var2+' from '+@var1
print @result

在上面的示例中，输出为select typecode from cctl_country。它也应该像select cctl_country,typecode from cctl_country一样。 table_name应该跟着typecode。

但是，扭曲的是@ var1是动态的并且不断变化，这需要从信息模式中检索。因此，对于@ var1值的每次更改，我都需要执行select查询并将结果集插入另一个表中。我在下面的代码中尝试了同样的事情但是我被卡住了。一点帮助将不胜感激

CREATE PROCEDURE usp_try
AS
BEGIN
    DECLARE @StartLoop INT
    DECLARE @EndLoop INT
    DECLARE @esal INT
    DECLARE @sqlquery varchar(max)

    DECLARE @Result TABLE (table_name nvarchar(100),typecodes nvarchar(100))
    DECLARE @InitResult TABLE (id INT IDENTITY(1, 1),
                         table_name NVARCHAR(50),
                         typecode NVARCHAR(50))

   INSERT INTO @InitResult
    select  col.TABLE_NAME,'typecodes' as typecodes from [NFUM_Studio].INFORMATION_SCHEMA.COLUMNS col
inner join [NFUM_Studio].INFORMATION_SCHEMA.TABLES tab
on col.TABLE_NAME = tab.TABLE_NAME
where col.COLUMN_NAME = 'typecode' 

    SELECT @StartLoop = MIN(ID),
         @EndLoop = MAX(ID)
    FROM @InitResult

    WHILE @StartLoop <= @EndLoop
       BEGIN

          SET @sqlquery = 'insert into @Result
                          select table_name,typecode from @InitResult'


          SET @StartLoop = @StartLoop + 1
       END

    SELECT *
    FROM @Result
END

Answer 1

尝试使用Temp Table而不是Table变量，并且不需要将Information_Schema.Columns表与Information_Schema.Tables连接起来。您也错过了执行@strQuery中存储的查询，只需使用EXEC(@strQuery)

CREATE PROCEDURE usp_try
AS
BEGIN
    DECLARE @StartLoop INT
    DECLARE @EndLoop INT
    DECLARE @esal INT
    DECLARE @sqlquery varchar(max)

    CREATE TABLE #Result(table_name nvarchar(100),typecodes nvarchar(100))
    CREATE TABLE #InitResult(id INT IDENTITY(1, 1),
                         table_name NVARCHAR(50),
                         typecode NVARCHAR(50))

   INSERT INTO #InitResult
    select  col.TABLE_NAME,'typecodes' as typecodes from [NFUM_Studio].INFORMATION_SCHEMA.COLUMNS col
    where col.COLUMN_NAME = 'typecode' 

    SELECT @StartLoop = MIN(ID),
         @EndLoop = MAX(ID)
    FROM @InitResult

    WHILE @StartLoop <= @EndLoop
       BEGIN

        SET @sqlquery = 'insert into #Result SELECT * FROM ('


        SELECT @sqlquery = @sqlquery + 'SELECT ''' + Table_name + ''' as [Table_name], [' + type_code + '] FROM ' + Table_name ' UNION ALL '
        FROM #InitResult


        SET @sqlquery = SUBSTRING(@strquery,1,LEN(@strquery) - 11)


        SET @sqlquery = @sqlquery + ' ) AS T1'


        EXEC(@strquery)




          SET @StartLoop = @StartLoop + 1
       END

    SELECT *
    FROM #Result
END

Answer 2

最后我能够获得输出，但是在光标的帮助下

DECLARE @@CC_TABLENAME VARCHAR(255)
declare @cc_exec varchar(255)
declare @cc_table varchar(255)
create table #temp(table_name varchar(max),typecode varchar(max))
DECLARE @CSR_TL AS CURSOR;

SET @CSR_TL = CURSOR FOR 

select  col.TABLE_NAME from [NFUM_Studio].INFORMATION_SCHEMA.COLUMNS col
where col.COLUMN_NAME = 'typecode' 


OPEN @CSR_TL

FETCH NEXT FROM @CSR_TL INTO @@CC_TABLENAME
WHILE @@FETCH_STATUS = 0
BEGIN

    set @cc_exec = 'insert into #temp(typecode) select typecode from '+@@CC_TABLENAME
    exec(@cc_exec)
    set @cc_table = 'update #temp set table_name='''+@@CC_TABLENAME+''' where table_name is null'
    exec(@cc_table)

    FETCH NEXT FROM @CSR_TL INTO @@CC_TABLENAME
END

--drop table #temp

CLOSE @CSR_TL
DEALLOCATE @CSR_TL

在select语句中使用行值作为列

2 个答案: