ps:说明显示带有href的详细信息:https://segmentfault.com/q/1010000014649728 我运行以下sql:
select * from
(
select *,(@num2 :=
(if(@GROUP199=`C_ISHOT`,@num2+1,if(@GROUP199:=`C_ISHOT`,1,1)))) row_number
from city_code order by C_ISHOT
) result
where row_number<=10
第一个运行结果显示表格总数, 但是第二个运行结果是我的预期。它有什么问题,我该如何解决?
答案 0 :(得分:0)
变量未初始化。
select *
from ( select *, (@num2 :=(if(@GROUP199=C_ISHOT,@num2+1,if(@GROUP199:=C_ISHOT,1,1)))) row_number
from city_code, ( SELECT @num2 := 0, @GROUP199 := 0 ) init_vars
order by C_ISHOT ) result
where row_number<=10