How to use DISTINCT and ORDER BY in same SELECT statement?

Use GROUP BY for Combination of DISTINCT and ORDER BY

Starving for some order in your distinct values? Combine GROUP BY and an aggregate function like MAX to feast on what you desire.

-- Ready for a trip down the rabbit hole?
SELECT Category, MAX(CreationDate) AS LatestDate
FROM your_table
GROUP BY Category
ORDER BY LatestDate DESC;


Here you get distinct Category values served hot and sorted by the most recent CreationDate.

Employ Subqueries to Handle Complex Sorting

For anyone who thought SQL was just a four-letter word, surprise! Subqueries to the rescue for constructing multi-step sorting criteria:

-- In SQL, we nest 'em like a Russian doll 
SELECT DISTINCT Category
FROM (
  SELECT Category, CreationDate
  FROM your_table
  ORDER BY CreationDate DESC
) AS SubTable
ORDER BY Category;


Inner query sorts the data first, then DISTINCT in the outer query keeps that order intact. SQLception!

Sort Within Your Means: Performance and Limitations

Nothing in life is free, not even SQL queries. More columns in ORDER BY potentially mean slower queries, so remember to check the cost.

-- To optimize, or not to optimize, that is the question
SELECT DISTINCT column1, column2
FROM your_table
ORDER BY column1, column2, column3;


This might optimize or slow down your query, context is key, not all heroes wear capes!

Beware the SQL standards

Knowing your database system's quirks will save you from a lot of facepalms. In SQL standards, some database engines mandate that ORDER BY columns be in the select list.

SQL Execution Order Know-How

By unravelling the SQL evaluation sequence, you can save yourself from a headache. GROUP BY is processed before ORDER BY. Understanding this can help you leverage the database engine's logic to your advantage.

Master the Fine Art of Subqueries and Joins

Capitalizing on subqueries and joins can aid in navigating the labyrinth of multiple table conditions and queries, where DISTINCT and ORDER BY alone may not suffice.

Be Wary of Column Selection

Picking columns for DISTINCT can change the game. Keep in mind that adding more columns may make your result too granular than intended. (Yes, you can have too much of a good thing!)