Indexes in SQL

Is it possible to set indexes between tables in SQL expression?

You can establish indexes on SQL tables, but SQL indexes do not create an implied relationship between tables. If you are familiar with PC databases like dBASE, SQL indexes are completely different ? to indicate a relationship between tables in SQL, you need to use the syntax in the CREATE TABLE command that establishes PRIMARY and FOREIGN keys. If your SQL database does not support referential integrity (PRIMARY and FOREIGN keys), you will not be able to establish a formal relationship between two tables. Even without referential integrity,this does not keep you from treating two tables as if they are related.If you need to retrieve data from two logically related tables, you simplyperform an equijoin, something like this:

        SELECT Orders.ordernumber, Items.quantity, Items.partno                FROM Orders, Items                WHERE Orders.ordernumber = Items.ordernumber;

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


The Latest

iOS app development

The Future of iOS App Development: Trends to Watch

When it launched in 2008, the Apple App Store only had 500 apps available. By the first quarter of 2022, the store had about 2.18 million iOS-exclusive apps. Average monthly app releases for the platform reached 34,000 in the first half of 2022, indicating rapid growth in iOS app development.

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