Get Table Primary Key Column In SQL

In this blog, we will discuss how we can get the primary column name of any table programmatically. However, we can see the primary column name by just right-clicking on a table and seeing the design view. But when we have dynamically created a table and set the primary key, then we do not know the primary column name. So in this article, we discuss that.

In my database, I have only one table named Employee, and you can see in the below image the primary key column is EmployeeId.

Employee Table

Here we use INFORMATION_SCHEMA.TABLE_CONSTRAINTS and INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE view, so first, we get what's inside that view.

Run the following queries to get the output of both views.

INFORMATION_SCHEMA.TABLE_CONSTRAINTS

select * from INFORMATION_SCHEMA.TABLE_CONSTRAINTS

Output

Schema Table

INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE

select * from INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE

Output

Column Usage

How to get Primary Key Column Name Programmatically?

Here are a few lines of SQL query using which we can get the primary column name.

select C.COLUMN_NAME FROM
INFORMATION_SCHEMA.TABLE_CONSTRAINTS T
JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE C
ON C.CONSTRAINT_NAME=T.CONSTRAINT_NAME
WHERE
C.TABLE_NAME='Employee'
and T.CONSTRAINT_TYPE='PRIMARY KEY'

Output

Output

Explanation

Here we join these two views, TABLE_CONSTRAINTS And CONSTRAINT_COLUMN_USAGE on CONSTRAINT_NAME.
Then select those records where CONSTRAINT_COLUMN_USAGE.TABLE_NAME is Employee and TABLE_CONSTRAINTS.CONSTRAINT_TYPE is the Primary Key.
And then, select CONSTRAINT_COLUMN_USAGE. COLUMN_NAME.

So that is just two or three lines of SQL query for getting the primary column name of any table. I hope you find some useful information in this article. If you find this helpful, kindly share it with your friends.