DEV Community

Cover image for A Brief Guide to SQL DELETE Queries
DbVisualizer
DbVisualizer

Posted on

A Brief Guide to SQL DELETE Queries

DELETE queries help remove unnecessary or incorrect data from your database. This short guide outlines their structure and practical usage.

The basic form of a DELETE query looks like this:

DELETE FROM table_name 
WHERE condition;
Enter fullscreen mode Exit fullscreen mode

Some helpful options include these four alternatives.

LOW_PRIORITY: Executes the query with lower priority.

QUICK: Optimizes how indexes are handled during deletion.

IGNORE: Ignores errors and continues deleting.

LIMIT: Deletes a specified number of rows.

Working with Partitions

For partitioned tables, DELETE queries can remove data from specific sections:

DELETE FROM table_name PARTITION (partition_name) 
WHERE condition;
Enter fullscreen mode Exit fullscreen mode

Alternatively, using TRUNCATE can speed up deletion:

TRUNCATE table_name PARTITION (partition_name);
Enter fullscreen mode Exit fullscreen mode

FAQ

What distinguishes DELETE from TRUNCATE?

DELETE selectively removes rows; TRUNCATE clears the whole table or partition. TRUNCATE is faster and has less overhead.

Can DELETE queries be made faster?

Yes, eliminating unnecessary indexes can improve performance.

When should DELETE be used over TRUNCATE?

DELETE should be used for specific data removal, while TRUNCATE is ideal for clearing all data.

What role does WHERE play in DELETE queries?

WHERE specifies which rows to delete, ensuring precision.

Summary

DELETE queries are fundamental in maintaining database efficiency. Knowing when to use them and understanding their variations, like TRUNCATE, can significantly optimize performance. For further reading and detailed examples, visit the original article DELETE Queries – Advanced CRUD explanation part 4.

Image of Docusign

Bring your solution into Docusign. Reach over 1.6M customers.

Docusign is now extensible. Overcome challenges with disconnected products and inaccessible data by bringing your solutions into Docusign and publishing to 1.6M customers in the App Center.

Learn more

Top comments (0)

AWS Security LIVE!

Tune in for AWS Security LIVE!

Join AWS Security LIVE! for expert insights and actionable tips to protect your organization and keep security teams prepared.

Learn More

👋 Kindness is contagious

Explore a sea of insights with this enlightening post, highly esteemed within the nurturing DEV Community. Coders of all stripes are invited to participate and contribute to our shared knowledge.

Expressing gratitude with a simple "thank you" can make a big impact. Leave your thanks in the comments!

On DEV, exchanging ideas smooths our way and strengthens our community bonds. Found this useful? A quick note of thanks to the author can mean a lot.

Okay