I have many tables with existing 'unique clustered' indexes. I would like to be able to add the 'primary key' attribute without dropping/recreating the clustered index. Is this p...
To enforce uniqueness, SQL Server creates a unique clustered index on the columns where Primary Keys were created out. If there are any existing clustered indexes, SQL Server creates a Unique Non-clustered index on the table for the Primary Key. Let’s see how we Create, Modify, Drop, Disa...
you wouldn’t be able to identify the car uniquely. The license plate differs in both instances, providing a good unique identifier for every row in the table. Because a license plate number is already part of the data, using that as a primary key would create a natural...
I have a table in my database which is populated with data. I need to add a second primary key in order to make up a composite key. How can I use this using strictly SQL ? Here is an example of what I am talking about: USE [Wonder] GO /*** Object: Table [dbo].[Fruits] ...
ADD KEY `status` (`status`) USING BTREE; CREATE TABLE `oc_product_to_category` ( `product_id` int(11) NOT NULL, `category_id` int(11) NOT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8; ALTER TABLE `oc_product_to_category` ADD PRIMARY KEY (`product_id`,`category_id`), ...
While it's true that you cannot addIDENTITYto an existing column, and that addingIDENTITYto an ...
While it's true that you cannot addIDENTITYto an existing column, and that addingIDENTITYto an ...
Why not change Table B so that the primary key is an identity which auto-increments?
CREATE TABLE [dbo].[Fruits] ( [Id] INT NOT NULL, [Perishable] BIT DEFAULT ((1)) NULL, PRIMARY KEY CLUSTERED ([Id] ASC), FOREIGN KEY ([Id]) REFERENCES [dbo].[Products] ([Id]) ); 单击Transact-SQL 编辑器工具栏中的“执行查询”按钮以便运行此查询。 右键单击“SQL Server 对象资源管理...
Hi, I am trying to modify the primary key of a table. We need to add new field and make it part of the Primary key of the table. I thought I can use this SQL Statement. ALTER TABLE tablename DROP PRIMARY KEY I got error "Syntax error in ALTER TA