Question

SQL语句的意思

请问这个语句对数据1209是什么意思
delete from dbo.Record_Data where infoid in (
select id from dbo.Dev_Info where sn = '40616172N') and [DevTime] between'2015-09-10 09:36:00.000' and '2015-09-12 11:00:00.000'
delete from dbo.Record_Channel where infoid in (
select id from dbo.Dev_Info where sn = '40616172N') and [DevTime] between '2015-09-10 09:36:00.000' and '2015-09-12 11:00:00.000'
最好每条语句都解释下，谢谢

Answer 1

Answer 2

创建表income_state，取housing表的hinc的平均值后保留整数，同时更名为income，取fips表的name字段，同时更名为state。并以name分组，就是取唯一值。以income字段分布，最终生成的表如下： 表名 income_state 有两个字段 state和income

追问

这都是什么跟什么啊.....