sql常用小命令

1.id从头开始

truncate table  表名

2.对一个字段取反吧

update topic set {0}=abs({0}-1) where ArticleId={1}

3，返回上次插入的ID值

select @@Identity

4.算出text字段的最大长度

  select datalength(contents) as suma,[ArticleId],title from topic order by suma desc