Question

我希望从多个表（MainTbl）中进行选择，但它将基于将拉出表的结果集（StateTbl）。

MainTables dbo.TABLE_MO，dbo.TABLE_CA，dbo.TABLE_AL，dbo.TABLE_MI

仅根据结果集StateTbl MO，CA，WA

进行拉取

Declare @Loop_Count int = 0
DECLARE @State varchar(2)
DECLARE @SQL varchar(max)

DECLARE db_cursor CURSOR FOR SELECT State FROM StateTbl

OPEN db_cursor

FETCH db_cursor INTO @State

WHILE (@@FETCH_STATUS = 0) 
BEGIN 


SET @SQL = 
'
    dbo.TABLE_'+ @State +'
'
EXEC(@SQL)

SET @Loop_Count = @Loop_Count + 1
FETCH db_cursor INTO @SQL

END
CLOSE  db_cursor
DEALLOCATE db_cursor

Answer 1

您可以利用dynamic和StateTbl来构建动态sql，而不是循环。这样的事情。

declare @SQL nvarchar(max) = ''

select 'select * from TABLE_' + [State] + ' UNION ALL '
from StateTbl

select @SQL = left(@SQL, len(@SQL) - 10)

select @SQL
--uncomment the line below when you satisfied the dynamic sql is written the way you want it.
--exec sp_executesql @SQL

在SELECT FROM循环中传递变量

1 个答案: