Query Processing Order

1. Getting Data (From, Join)
2. Row Filter (Where)
3. Grouping (Group by)
4. Group Filter (Having)
5. Return Expressions (Select)
6. Duplicate Filter (Distinct)
7. Order & Paging (Order by & Limit / Offset)

IMPORTANT

• In the WHERE clause we cannot use Alias this is because the WHERE clause is executed before the SELECT statement
• In ORDER BY clause we can pass alias as it is processed after the SELECT statement

SQLBolt - Learn SQL - SQL Lesson 12: Order of execution of a Query

The 6 Steps of a SQL Select Statement Process | by Wendy Navarrete