Use SQL Server Management StudioIn Object Explorer, right-click the table to which you want to add a unique constraint, and select Design. In Table Designer, select the row selector for the database column you want to define as the primary key. If you want to select multiple columns, ...
如图所示的软件界面,设定SQL Server实例,选取数据库名字,输入要改变成的排序规则,点击处理,即可生成包含7个步骤运行的SQL语句,把这7个SQL语句依次放到数据库中执行一次,即可改变它的排序规则。 1 Prepare Procedure 准备程序,先要运行一下,以生成创建SQL Server Constraint/Index的脚本。 有五个关键的存储过程要先运...
While SQL Server only allows one PRIMARY KEY constraint assigned to a single table, that PRIMARY KEY can be defined for more than one column. In a multi-column scenario, individual columns can contain duplicate, non-unique values, but the PRIMARY KEY constraint ensures that every combination of...
CONSTRAINT uc_PersonID PRIMARY KEY (Id_P,LastName) ) 1. 2. 3. 4. 5. 6. 7. 8. 9. 如果需要命名 PRIMARY KEY 约束,以及为多个列定义 PRIMARY KEY 约束,请使用下面的 SQL 语法: ALTER TABLE Persons ADD CONSTRAINT pk_PersonID PRIMARY KEY (Id_P,LastName) 1. 2. 2:FOREIGN KEY约束 外键(...
If a primary key constraint is defined on more than one column, values can be duplicated within one column, but each combination of values from all the columns in the primary key constraint definition must be unique.As shown in the following illustration, the ProductID and VendorID colum...
(255), CONSTRAINT pk_PersonsID PRIMARY KEY (Id_P,LastName) ) 在 表已存在的情况下为"Id_P"列创建PRIMARY KEY 约束 MySQL/SQL Server/Oracle/MS Access ALTER TABLE Persons ADD PRIMARY KEY (Id_P) 命名PRIMARY KEY 约束,以及为多个列定义 PRIMARY KEY 约束 MySQL SQL Server/Oracle/MS Access ALTER ...
Use SQL Server Management Studio Delete a primary key constraint using Object Explorer In Object Explorer, expand the table that contains the primary key and then expandKeys. Right-click the key and selectDelete. In theDelete Objectdialog box, verify the correct key is specified and selectOK. ...
Using Transact-SQL To modify a primary key To modify a PRIMARY KEY constraint using Transact-SQL, you must first delete the existing PRIMARY KEY constraint and then re-create it with the new definition. For more information, seeDelete Primary KeysandCreate Primary Keys....
also permits fast access to data when the primary key is used in queries. If a primary key constraint is defined on more than one column, values can be duplicated within one column, but each combination of values from all the columns in the primary key constraint definition must be unique....
Keep in mind that in order to use a column in the primary key, the field must not be nullable.[cc lang=”sql”] CREATE TABLE [dbo].[Person]( PersonID [int] IDENTITY(1,1) NOT NULL, FirstName VARCHAR(50) NOT NULL CONSTRAINT PK_Person PRIMARY KEY NONCLUSTERED (PersonID, FirstName)...