sql server中的exec和sp_executesql

参考地址：http://www.cnblogs.com/xbf321/archive/2008/11/02/1325067.html

exec('select * from TableName')

declare @slideAvg real
declare @sql1 nvarchar(1000)
set @sql1='select @slideAvg=avg(val) from S'+@StationID+'HN where channel_num='''+@channel_num+''' and date_time>='''+convert(nvarchar,@oldH,120)+''' and date_time<='''+convert(nvarchar,@h24,120)+''''
exec sp_executesql @sql1,N'@slideAvg real output',@slideAvg output
IF @slideAvg IS NOT NULL AND @slideAvg<>''
begin
    .........
end

SELECT  C0252_ID, C0252_name,C0252_Addr,
((select top 1 C0003_Name from dbo.T0003_DistrictInfo where c0003_code like '%'+SUBSTRING(C0003_AreaCode,1,4)+'%')+' '+C0003_AreaName) as AreaName
FROM   dbo.T0252_Manufacturer