FAQ   SQL FAQ


Topic Replies Activity
About the SQL FAQ category 1 December 30, 2017
How can we get the average of unique values of a column? 3 October 8, 2019
How do we search for patterns containing the actual characters "%" or "_"? 4 January 25, 2020
Is the `AND` used in `BETWEEN` the same as the `AND` operator between conditions? 2 March 31, 2020
What are some ways that SQL is used in data science? 2 January 9, 2020
Can a WHERE clause be applied with a HAVING statement in the same query? 1 August 4, 2018
Can we alias multiple columns in a single query? 3 March 26, 2020
Does the result change if we JOIN tables in a different order? 2 November 19, 2019
Can you CROSS JOIN on more than two tables? 5 March 25, 2020
Does the order of tables in a JOIN matter? 3 September 1, 2019
Can we apply ORDER BY with multiple columns? 9 February 12, 2020
When should I use INNER JOIN instead of LEFT JOIN? 8 February 24, 2020
What are some reasons to apply constraints to a table? 11 February 15, 2020
When do we use COUNT() or SUM()? 7 January 6, 2020
FAQ: Why Data Science? - Exploring Data with SQL 11 March 10, 2020
When using GROUP BY, do we always have to group by a selected column? 3 February 16, 2020
What's the difference between COUNT(1), COUNT(*), and COUNT(column_name)? 10 December 7, 2019
What order are rows selected from a table? 1 November 5, 2018
Can we add a column at a specific position to a table? 3 July 14, 2019
Is there a shorter way to insert multiple rows in a table? 19 February 15, 2020
When should we use each type of JOIN? 1 August 24, 2018
Is it possible for a table to have more than one unique identifier column? 6 March 28, 2020
How does this statement tell us if a user is active or not active? 5 November 29, 2019
When applying the BETWEEN operator on TEXT values, how are values compared? 3 January 23, 2020
Does COUNT() include duplicate values of a column? 3 February 13, 2020
Can we write conditions using both AND and OR? 10 March 31, 2020
Do SQL clauses always have to be entirely capitalized? 5 February 21, 2020
What if we only want to delete a specific number of rows? 18 January 17, 2020
Does every SQL statement follow this structure? 3 August 17, 2019
How is ALTER different from UPDATE? 4 March 16, 2020