IF EXISTS (SELECT * FROM sysobjects WHERE name = 't_dispatchBill_entry' AND xtype = 'U') DROP TABLE t_dispatchBill_entry GO 在ms sql中当我们需要修改表结构的时候,有时候因为添加或修改的表字段存在或不存在而导致后面的sql脚本执行失败。 这时我们需要一个语句来判断当前字段的有效性。然后再执行我...
一、检测数据库是否存在于当前数据库引擎下 ifexists(select*fromsys.databaseswherename=’数据库名称’)beginprint'数据库名称--存在'end 二、检测数据表是否存在于指定数据库下 ifexists(select*fromsysobjectswhereid=object_id(N’[数据表名称]’)andOBJECTPROPERTY(id, N’IsUserTable’)=1)beginprint'数据表...
主键约束(PK Primary key) 唯一键约束(UQ unique) 外键约束(FK foreign key) 默认值约束(DF default) check约束(CK check) 语法: alter table 表名 add constraint 前缀_约束名称 约束类型 约束说明(字段 关系表达式 值) 5 四中基本字符类型说明 6 SQL基本语句 数据插入 调用方法 一 ...
Create a table 显示另外 3 个 In this quickstart, you learn how to use the MSSQL extension for Visual Studio Code to connect to a database, whether it's running locally, in a container, or in the cloud. Then you learn how to use Transact...
Verify that the SQL Server login exists and that you've spelled it properly. If the login doesn't exist, create it. If it's present but misspelled, correct that in the application connection string. The SQL Server Errorlog will have one of the following messages:- Login failed for user ...
IF NOT EXISTS (SELECTnameFROMsys.databasesWHEREname= N'Library')CREATEDATABASELibrary; This script creates a new database calledLibraryif it doesn't already exist. The newLibrarydatabase appears in the list of databases. If you don't see it immediately, refresh the Object Explorer. ...
由于工作原因,程序需要适配两种类型的数据库,所以把一些sql语句写法对比总结一下本篇及后续随笔都将使用一个极其简单的场景(课室,学生,1对多)来演示,请先创建表mysqlCREATE TABLE IF NOT EXISTS `class` ( `Id` int(11) NOT NULL, `Name` varchar(50) NOT NULL DEFAULT '0', PRIMARY mysql和oss 的区别...
IF NOT EXISTS( SELECT * FROM sys.symmetric_keys WHERE name = '##MS_ServiceMasterKey##') BEGIN CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'MSSQLSerivceMasterKey' END; GO 创建数据库级别Master Key 在用户数据库TestDb数据库下,创建Master Key: ...
文件增长方式) */ if exists(select * from sys.databases where name='MyNewDb') drop database MyNewDb--删除数据库...sp_helpdb MyNewDb --修改数据库的名称:sp_renamedb 旧数据库名,新数据库名 sp_renamedb MyNewDb,MyDBDB --修改数据库alter database...--建立带主键的约束 Create table ...
IF EXISTS(SELECT ID, StartTime, EndTime, EventName, UserID, Details FROM EventTable WHERE (DATEPART(day, StartTime) = DATEPART(day, @startTime)) AND (UserID=@userID)) BEGIN SELECT 'This record already exists!' END ELSE BEGIN SELECT 'This record does not exist!' ...