1 -------------------------一,数据库操作-----------------------------  2 ------------1,创建数据库------------------  3 IF DB_ID(‘TestDB‘) IS NOT NULL DROP DATABASE TestDB;  4   5 CREATE DATABASE TestDB ON   6 (  7     NAME=‘TestDB‘,  8     FILENAME=‘d:\mcgrady\db\TestDB.mdf‘,  9     SIZE=4, 10     MAXSIZE=10, 11     FILEGROWTH=1 12 ); 13  14 ------------2,备份数据库------------------ 15 BACKUP DATABASE TestDB TO DISK=‘d:\mcgrady\db\bak\TestDB.bak‘; 16  17 ------------4,删除数据库------------------ 18 --IF DB_ID(‘TestDB‘) IS NOT NULL DROP DATABASE TestDB; 19  20 ------------5,删除数据库日志文件------------------ 21 --DBCC ERRORLOG 22 --GO 6 23  24 -------------------------二,数据表操作----------------------------- 25 USE TestDB; 26 GO 27 ------------1,创建数据表------------------ 28 IF OBJECT_ID(‘dbo.SM_User‘) IS NOT NULL DROP TABLE dbo.SM_User; 29  30 CREATE TABLE SM_User 31 ( 32     ID INT NOT NULL IDENTITY, 33     UserId NVARCHAR(20) NOT NULL, 34     PASSWORD NVARCHAR(20) NOT NULL, 35     NAME NVARCHAR(20) NOT NULL, 36     Gender TINYINT NULL 37         CONSTRAINT DFT_User_Gender DEFAULT(0), 38     CreateTime DATETIME NULL 39         CONSTRAINT DFT_User_CreateTime DEFAULT(GETDATE()), 40     DESCRIPTION NVARCHAR(max) NULL, 41     CONSTRAINT PK_SM_User PRIMARY KEY(ID) 42 ); 43  44 ------------2,删除数据表------------------ 45 --IF OBJECT_ID(‘dbo.SM_User‘) IS NOT NULL DROP TABLE dbo.SM_User; -- 也可以使用TRUNCATE TABLE 46  47 -------------------------三,字段操作----------------------------- 48 ------------1,添加字段------------------ 49 ALTER TABLE dbo.SM_User ADD Item1 NVARCHAR(MAX) NULL; 50  51 ------------2,修改字段------------------ 52 ALTER TABLE dbo.SM_User ALTER COLUMN Item1 NVARCHAR(50); 53  54 ------------3,删除字段------------------ 55 ALTER TABLE dbo.SM_User DROP COLUMN Item1; 56  57 ------------4,添加约束------------------ 58 ALTER TABLE dbo.SM_User ADD CONSTRAINT chk_user_createtime CHECK(CreateTime<=GETDATE()); 59  60 ------------5,删除约束------------------ 61 ALTER TABLE dbo.SM_User DROP CONSTRAINT chk_user_createtime; 62  63 ------------6,添加默认值---------------- 64 ALTER TABLE dbo.SM_User ADD CONSTRAINT DFT_User_Password DEFAULT ‘123‘ FOR PASSWORD; 65  66 ------------7,删除默认值---------------- 67 ALTER TABLE dbo.SM_User DROP CONSTRAINT DFT_User_Password; 68  69 ------------8,数据表和字段描述信息操作---------------- 70 --为表添加描述信息   71 EXEC sp_addextendedproperty N‘MS_Description‘ , N‘人员信息表‘ , N‘SCHEMA‘ , N‘dbo‘ , N‘TABLE‘ , N‘表名‘ , NULL , NULL   72    73 --为字段XingMing添加描述信息   74 EXEC sp_addextendedproperty N‘MS_Description‘ , N‘姓名‘ , N‘SCHEMA‘ , N‘dbo‘ , N‘TABLE‘ , N‘表名‘ , N‘COLUMN‘ , N‘XingMing‘   75    76 --更新表中列XingMing的描述属性：   77 EXEC sp_updateextendedproperty N‘MS_Description‘ , N‘真实姓名‘ , N‘SCHEMA‘ , N‘dbo‘ , ‘TABLE‘ , ‘表名‘ , ‘COLUMN‘ , N‘XingMing‘   78    79 --删除表中列XingMing的描述属性：   80 EXEC sp_dropextendedproperty N‘MS_Description‘ , N‘SCHEMA‘ , N‘dbo‘ , ‘TABLE‘ , ‘表名‘ , ‘COLUMN‘ , N‘XingMing‘  81  82 -------------------------四,其它操作----------------------------- 83 ------------1,清除查询缓存---------------- 84 DBCC FREEPROCCACHE 85 DBCC DROPCLEANBUFFERS 86 ------------2,随机取10条数据-------------- 87 SELECT TOP 10 * FROM [表名] ORDER BY NEWID(); 88  89 ------------3,以逗号连接结果集所有行,使之变为一行---------------- 90 DECLARE @result NVARCHAR(MAX)   91 SET @result = N‘‘   92 SELECT @result = @result + N‘,‘ + Name FROM @Student   93    94 SELECT RIGHT(@result,LEN(@result) - 1); 95  96 ------------4,向数据库中添加n条数据---------------- 97 DECLARE @i int   98 SET @i=1   99 WHILE @i<=5000  100 BEGIN  101   INSERT INTO users(userid,username) VALUES (@i,‘username‘ convert(varchar(255),@i));102   SET @i=@i+1  103 END