Apr 08, 2020 Live, Learn, Share. I get asked this every now and again, along with the companion When was the last time this login was. Apr 24, 2007 This article by Jeff Smith covers different ways to create sequence numbers. It starts with the basic identity and GUIDs and quickly moves to much more complicated sequence numbers including those with auto-incrementing mixed letters and numbers such as 'A0001', etc. Jeff shows one of the easiest ways I've ever seen to efficiently handle very odd sequence numbers.
-->You can define a primary key in SQL Server by using SQL Server Management Studio or Transact-SQL. Creating a primary key automatically creates a corresponding unique clustered index, or a nonclustered index if specified as such.
Before You Begin
![Surrogate Surrogate](/uploads/1/2/6/1/126141007/444945956.png)
Limitations and Restrictions
Stored Proc Sql
- A table can contain only one PRIMARY KEY constraint.
- All columns defined within a PRIMARY KEY constraint must be defined as NOT NULL. If nullability is not specified, all columns participating in a PRIMARY KEY constraint have their nullability set to NOT NULL.
Stored Proc For Generating Surrogate Keys Free
Security
Permissions
Creating a new table with a primary key requires CREATE TABLE permission in the database and ALTER permission on the schema in which the table is being created.
Creating a primary key in an existing table requires ALTER permission on the table.
Using SQL Server Management Studio
To create a primary key
- In Object Explorer, right-click the table to which you want to add a unique constraint, and click Design.
- In Table Designer, click the row selector for the database column you want to define as the primary key. If you want to select multiple columns, hold down the CTRL key while you click the row selectors for the other columns.
- Right-click the row selector for the column and select Set Primary Key.
Caution
If you want to redefine the primary key, any relationships to the existing primary key must be deleted before the new primary key can be created. A message will warn you that existing relationships will be automatically deleted as part of this process.
A primary key column is identified by a primary key symbol in its row selector.
If a primary key consists of more than one column, duplicate values are allowed in one column, but each combination of values from all the columns in the primary key must be unique.
If you define a compound key, the order of columns in the primary key matches the order of columns as shown in the table. However, you can change the order of columns after the primary key is created. For more information, see Modify Primary Keys.
![Stored Stored](/uploads/1/2/6/1/126141007/118753370.jpg)
Using Transact-SQL
To create a primary key in an existing table
Create Stored Proc
The following example creates a primary key on the column
TransactionID
in the AdventureWorks database.To create a primary key in a new table
The following example creates a table and defines a primary key on the column
TransactionID
in the AdventureWorks database.To create a primary key with clustered index in a new table
The following example creates a table and defines a primary key on the column
CustomerID
and a clustered index on TransactionID
in the AdventureWorks database.