Many Primary Keys for a Single Table

Have you ever wanted to have 1:1 relation between tables (i.e. a table in which two columns act like primary key not combined but separately)?

DB only supports a single column, or group of columns, as primary key. How do you get primary key behavior for 2 columns in DB?

Define one column a primary key and the other columns with Unique+NotNull constraint. This gives the columns all the features of Primary Key.

Note: This also works in SQL Server, Oracle, and MSAccess.

Share the Post:
Share on facebook
Share on twitter
Share on linkedin


The Latest

microsoft careers

Top Careers at Microsoft

Microsoft has gained its position as one of the top companies in the world, and Microsoft careers are flourishing. This multinational company is efficiently developing popular software and computers with other consumer electronics. It is a dream come true for so many people to acquire a high paid, high-prestige job

your company's audio

4 Areas of Your Company Where Your Audio Really Matters

Your company probably relies on audio more than you realize. Whether you’re creating a spoken text message to a colleague or giving a speech, you want your audio to shine. Otherwise, you could cause avoidable friction points and potentially hurt your brand reputation. For example, let’s say you create a

chrome os developer mode

How to Turn on Chrome OS Developer Mode

Google’s Chrome OS is a popular operating system that is widely used on Chromebooks and other devices. While it is designed to be simple and user-friendly, there are times when users may want to access additional features and functionality. One way to do this is by turning on Chrome OS