如何防止在SQL Server中重複的項不是主項字段

Question

這是我正在使用的插入語句。此表中的主鍵是的IDNumber

ALTER procedure [dbo].[AddCustomer] 
@IDNumber nvarchar(20), 
@Title nchar(10), 
@Name nvarchar(50), 
@Surname nvarchar(50), 
@CellPhone nchar(10), 
@AddressLine1 nvarchar(50), 
@Suburb nvarchar(40), 
@City nvarchar(30), 
@PostalCode nchar(10), 
@EmailAddress nvarchar(50), 
@Password nvarchar(20) 
as 

insert into Customer(IDNumber,Title,Name,Surname,CellPhone,AddressLine1,Suburb,City,PostalCode,EmailAddress,[Password]) 
values (@IDNumber,@Title,@Name,@Surname,@CellPhone,@AddressLine1,@Suburb,@City,@PostalCode,@EmailAddress,@Password) 

現在我想的SQL語句，將防止重複的電子郵件地址被插入。

Answer 1

你想看看唯一約束http://msdn.microsoft.com/en-gb/library/ms190024.aspx

ALTER TABLE Customer 
ADD CONSTRAINT UC_email UNIQUE (EmailAddress); 
GO 

Answer 2

您可以在電子郵件列上創建唯一索引/鍵。 CREATE UNIQUE INDEX IX_Email ON TABLE（EMAIL）;

Answer 3

這實際上應在表列的約束。

ALTER TABLE Customer 
ADD CONSTRAINT EmailAddress_Uniqueness_Constraint UNIQUE (EmailAddress)