sqlsql-serversql-server-2005

Execution sequence of Group By, Having and Where clause in SQL Server?

I am just confused with the execution sequence of a SQL query when we use GROUP BY and HAVING with a WHERE clause. Which one gets executed first? What is the sequence?

Solution

  • in order:

    FROM & JOINs determine & filter rows
    WHERE more filters on the rows
    GROUP BY combines those rows into groups
    HAVING filters groups
    ORDER BY arranges the remaining rows/groups
    LIMIT filters on the remaining rows/groups