日常方法
1.C#.NET 字符串转数组,数组转字符串
string str = "1,2,3,4,5,6,7";
string[] strArray = str.Split(','); //字符串转数组
str = string.Empty;
str = string.Join(",", strArray);//数组转成字符串
2.c# 三种取整方法 向上取整 向下取整 四舍五入
Math.Round:四舍六入五取整
Math.Ceiling:向上取整,只要有小数都加1
Math.Floor:向下取整,总是舍去小数
3.SqlServer 查询死锁,杀死死锁进程
-- 查询死锁 select request_session_id spid, OBJECT_NAME(resource_associated_entity_id) tableName from sys.dm_tran_locks where resource_type='OBJECT'
--杀死死锁进程 kill 354
4、查询在一个个表中有另一个表中没有的数据
select UserId,UserName from Users where UserId NOT in(select UserId from PxbUser where Users.UserId=PxbUser.UserId and PxbId=1) select UserId,UserName from Users where (select count(1) as num from PxbUser where PxbUser.UserId = Users.UserId and PxbUser.PxbId=1) = 0 --效率更高