SQL常用的设置和函数（1）
1.切换或打开数据库：USE 数据库名2.调整数据库的大小：USE testGOALTER DATABASE testMODIFY FILE(NAME='test'FILENAME='D:\XP\SQLDB\test.mdf',SIZE=20MB)
3.查看目前数据库选项设定及修改：EXEC sp_dboption '数据库' '选项参数'，True选项参数： trunc. log on chkpt --防止日志增长太快 dbo use only --只有数据库拥有者才能使用数据库 read only --可以检索数据，但不能修改 single user --每次只能一个用户访问 offline --数据库为离线状态 autoshrink --数据库将自动周期性收缩大小 ANSI warnings --提示‘除0’之类的标准错误和警告4.将数据库减缩的最小容量USE 数据库GODBCC SHRINKDATABASE(数据库)5.更改数据库名：EXEC sp_renamedb 'newname','oldname'
6.暂停控制命令 WAITFOR用来暂时停止程序执行，知道设定时间已过货已到达才继续往下执行WAITFOR { DELAY 'time' | TIME 'time'|ERROREXIT|PROCESSEXIT|MIRROREXIT }.DELAY:用来设定等待时间，最大24个小时.TIME:用来设定等待结束的时间点.ERROREXIT：直接处理非正常中断.PEOCESSEXIT:直接处理正常或非正常中断.MIRROREXIT:直到镜像设置失败ExamplesA. Use WAITFOR TIME This example executes the stored procedure update_all_stats at 10:20 P.M. BEGIN WAITFOR TIME '22:20' EXECUTE update_all_statsEND
B. Use WAITFOR DELAY This example shows how a local variable can be used with the WAITFOR DELAY option. A stored procedure is created to wait for a variable amount of time and then returns information to the user as to the number of hours, minutes, and seconds that have elapsed.CREATE PROCEDURE time_delay @@DELAYLENGTH char(9)ASDECLARE @@RETURNINFO varchar(255)BEGIN WAITFOR DELAY @@DELAYLENGTH SELECT @@RETURNINFO = 'A total time of ' + SUBSTRING(@@DELAYLENGTH, 1, 3) + ' hours, ' + SUBSTRING(@@DELAYLENGTH, 5, 2) + ' minutes, and ' + SUBSTRING(@@DELAYLENGTH, 8, 2) + ' seconds, ' + 'has elapsed! Your time is up.' PRINT @@RETURNINFOENDGO-- This next statement executes the time_delay procedure.EXEC time_delay '000:00:10'GOHere is the result set:A total time of 000 hours, 00 minutes, and 10 seconds, has elapsed! Your time is up.