Code -- Isolate top waits WITH Waits AS ( SELECT wait_type, wait_time_ms / . AS wait_time_s, . * wait_time_ms / SUM(wait_time_ms) OVER() AS pct, ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn, . * signal_wait_time_ms / wait_time_ms as signal_pct…
Select 分析一个查询实例 Select empid,year(orderdate) as orderYear,count(*) as orderCount From dbo.orderInfo where custid=71 group by empid,Year(orderdate) having count(*) >1 order by empid 以上语句在sql server内的执行顺序是 from--where--group by--having --select--order…
创建数据库: if db_id('DBTest') is nullcreate database DBTest 创建表 use eb_fy_data_test---use 切换所在数据库上下文 if object_id('UserTest','u') is not null drop TABLE UserTest CREATE TABLE UserTest {} 数据完整性 1.主键约束 alter table UserTest add constraint PK_UserTest Primar…
2.1 类型属性 2.1.1 UNSIGNED 数字无符号化, INT的值 -2147483648 ~ 2147483647 INT UNSIGNED的值 0 ~ 4294967295 int a = 1; int b = 2; a-b=-1 unsigned a = 1; unsigned b = 2; a-b=4294967295(Linux) Mac 报错 如果想要得到-1 mysql> SET sql_mode='NO_UNSIGNED_SUBTRACTION'; 2.1.2 ZER…
