Oct 20, 2008 · You can only have one primary key, but you can have multiple columns in your primary key. You can also have Unique Indexes on your table, which will work a bit like a primary key in that they will enforce unique values, and will speed up querying of those values.

To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: PRIMARY KEY (PK_Person). However, the VALUE of the primary key is made up of TWO COLUMNS (ID + LastName).

May 12, 2016 · you cannot create two primary keys in a table. You can combine two columns in a table and make as a single primary key. create table table1 ( col1 int, col2 varchar(20), .... Primary key (col1, col2) )

Feb 8, 2022 · CREATE TABLE dbo.PrimaryTable (ID int IDENTITY, SomeValue varchar(10) NULL, CONSTRAINT PK_PrimaryTable PRIMARY KEY (ID)); CREATE TABLE dbo.AnotherPrimaryTable (AnotherIdentifier uniqueidentifier NOT NULL, CONSTRAINT PK_AnotherPrimaryTable PRIMARY KEY (AnotherIdentifier)); GO CREATE TABLE dbo.PrimaryTableLink (ID int NOT NULL, AnotherIdentifier ...

To allow naming of a PRIMARY KEY constraint, and for defining a PRIMARY KEY constraint on multiple columns, use the following SQL syntax: PRIMARY KEY (PK_Person). However, the VALUE of the primary key is made up of TWO COLUMNS (ID + LastName).

Nov 11, 2024 · Recently, my team was required to create tables with multiple primary keys in SQL Server. We analyzed the requirement and identified a few simple approaches to achieve this. In this article, I will walk you through multiple ways to do this task. Remember that this is known as Composite Primary Key.

Aug 18, 2019 · This article provides an example of creating a composite primary key using Transact-SQL in SQL Server. You can create a composite primary key just as you would create a single primary key, except that instead of specifying just one column, you provide the name of two or more columns, separated by a comma. Like this:

Summary: in this tutorial, you will learn how to use the SQL PRIMARY KEY constraint to add a primary key to the table. A primary key is a column or a set of columns that uniquely identifies each row in the table. A primary key ensures that each row is unique. A table includes one and only one primary key.

Use a compound primary key: CREATE TABLE yourtable ( employeeid INT, blahblah VARCHAR(255), blahblah2 VARCHAR(255), recordmonth DATE, recordyear DATE, PRIMARY KEY (employeeid, recordmonth, recordyear) )

Aug 5, 2019 · This article demonstrates how to add a primary key to an existing table in SQL Server using Transact-SQL. A primary key is a column that has been configured as the unique identifier for a given table.