Tips for Writing Readable SQL Queries

Tips for writing quality SQL queries

1. Use UPPER CASE for keywords

`SELECT`, `FROM`, `WHERE`, `JOIN` - in upper case. This visually separates the keywords from the data.

2. Give tables aliases

Short, meaningful aliases (`users AS u`) make JOIN queries easier to read.

3. Avoid SELECT *

Explicitly specify the required columns. This improves performance and makes the query self-documenting.

4. Comment on difficult conditions

Add comments to non-obvious WHERE conditions and business logic.

5. Use CTEs instead of subqueries

Common Table Expressions (WITH) make complex queries modular and readable.

6. Format CASE expressions

Each WHEN is indented on a new line. END - at the CASE level.

7. Group JOIN conditions

Each JOIN is on a new line. The ON condition is indented under JOIN.

8. Use a consistent style across the team

Fix the SQL formatting rules in the project style guide.

See also: JSON Formatter, Diff Checker, Regex tester