日期:2014-05-19  浏览次数:20571 次

优化求解:上万条带参数的查询语句
手头的一个活,可以简化为以下模型:

declare   @i   int,   @j   int,   @iCount   int
set   @i   =   0
set   @j   =   0

while(@i   <   100)
begin
        while(@j   <   100)
        begin
                set   @iCount   =   (select   count(*)   from   table1   where   field1   =   @i   and   field2   =   @j)
                if   (@iCount   <>   0)
                begin
                        insert   into   table2(field1,   field2)   values(@i,   @j)
                end
                set   @j   =   @j   +1
        end
        set   @i   =   @i   +1
end

针对以上模型,求最佳效率的解决方案,比如通过临时表、批量执行或把多条select语句合成一条语句等等,诸位以为如何?

------解决方案--------------------
--try
declare @i int, @j int, @iCount int
set @i = 0
set @j = 0

while(@i < 100)
begin
while(@j < 100)
begin
insert into table2(field1, field2)
select @i, @j
where exists(select 1 from table1 where field1 = @i and field2 = @j)

set @j = @j +1
end
set @i = @i +1
end

------解决方案--------------------
insert into table2(field1, field2)
select field1,field2 from table1
WHERE field1 <100 AND field2 <100 GROUP BY field1,field2 HAVING count(1)> 0
------解决方案--------------------
楼上正解。