在这种情况下如何使用 EXEC 或 sp_executeSQL 而不循环? [英] How to use EXEC or sp_executeSQL without looping in this case?

问题描述

环境:SQL Server 2005/2008，pubs数据库

Environment: SQL Server 2005/2008, pubs database

我使用 information_schema 表将一组数据插入到表变量中，如下所示.

I have inserted into a table variable a set of data as shown below using information_schema tables.

现在我想根据在列 dSQL 中执行查询的结果更新标志列.我能够使用循环/游标进行​​更新，然后使用 sp_executeSQL更新列，然后更新标志列.但是有没有一种替代的基于集合的方法来循环通过所有单独的行来做到这一点?

Now I would like to update the flag column based on the result of executing the query in the column dSQL. I was able to update using loops/cursor and then used sp_executeSQL to update the column and then update flag column later. But is there an alternate set-based way to do this without looping through all individual rows?

use pubs
go

declare @dsql Nvarchar(max)='', @tablename varchar(100), @colname varchar(100)
declare @t table (
 TABLE_NAME varchar(100),
 COLUMN_NAME varchar(100)
)

insert into @t
select distinct t.TABLE_NAME, c.COLUMN_NAME
from information_Schema.tables t
inner join
information_Schema.columns c
on t.TABLE_CATALOG = c.TABLE_CATALOG
where t.TABLE_SCHEMA = c.TABLE_SCHEMA
and t.TABLE_TYPE = 'BASE TABLE'
and c.DATA_TYPE = 'varchar'

select *, Dsql = 'select ' + COLUMN_NAME +  ' from ' + TABLE_NAME + ' WHERE '
+ COLUMN_NAME + ' = ''Menlo Park''', '' as Flag
FROM @t
GO   

我有一个想法，创建一个函数并为每一行调用该函数来执行单独的查询语句，但为每条记录调用该函数可能会影响性能.

I had an idea to create a function and call the function for each row to execute individual query statement but calling the function for each record might be a performance hit.

推荐答案

不可能，我之前做了一个类似的脚本.

Not possible, I made a script like it earlier.

declare @searchvalue varchar(100)

set nocount off

set @searchvalue = 'Hello world'


create table #tt (table_name varchar(64), column_name varchar(64), count int)
select * into #t from 
(
select 'select ''' + a.table_name + ''' ''table_name'',''' + a.column_name + ''' ''column_name'', count(*) count from [' + a.table_name +'] where [' +a.column_name+']='''+@searchvalue +'''' + ' group by ['+ a.column_name+']' sqlstring
from INFORMATION_SCHEMA.COLUMNS a
join 
INFORMATION_SCHEMA.TABLES b
on a.table_name = b.table_name
and b.table_type = 'base table'
 where data_type = 'varchar'
) a

--loop cursor
Declare @sqlstring as nvarchar(500)
Declare SqlCursor CURSOR FAST_FORWARD FOR
SELECT sqlstring FROM #t
OPEN SqlCursor
FETCH NEXT FROM SqlCursor
INTO @sqlstring
WHILE @@FETCH_STATUS = 0
BEGIN
insert #tt
exec(@sqlstring)
     FETCH NEXT FROM SqlCursor
     INTO @sqlstring
END
CLOSE SqlCursor
DEALLOCATE SqlCursor
select * from #tt
drop table #tt
drop table #t

随心所欲

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