FAQ   SQL FAQ


Topic Replies Activity
About the SQL FAQ category 1 December 30, 2017
FAQ: Why Data Science? - Exploring Data with SQL 10 September 18, 2019
What if we only want to delete a specific number of rows? 11 September 16, 2019
Does COUNT() include duplicate values of a column? 1 August 4, 2018
When should I use INNER JOIN instead of LEFT JOIN? 5 November 22, 2019
Does the result change if we JOIN tables in a different order? 2 November 19, 2019
What are some reasons to apply constraints to a table? 8 September 26, 2019
When doing an INNER JOIN, are columns matched on NULL values? 3 November 11, 2019
Can a WHERE clause be applied with a HAVING statement in the same query? 1 August 4, 2018
How is ALTER different from UPDATE? 1 November 5, 2018
How does this statement tell us if a user is active or not active? 5 November 29, 2019
If multiple rows have the minimum or maximum value, which one is returned when using MAX/MIN? 3 June 2, 2019
Does the order of tables in a JOIN matter? 3 September 1, 2019
Is it possible for a table to have more than one unique identifier column? 3 November 19, 2019
Can we apply ORDER BY with multiple columns? 8 October 3, 2019
When do we use COUNT() or SUM()? 6 October 23, 2019
FAQ: Subqueries - Correlated Subqueries II 8 October 7, 2019
How can we get the average of unique values of a column? 3 October 8, 2019
FAQ: Aggregate Functions - Having 11 October 18, 2019
When applying the BETWEEN operator on TEXT values, how are values compared? 1 August 4, 2018
Is the `AND` used in `BETWEEN` the same as the `AND` operator between conditions? 1 August 4, 2018
Can we add a column at a specific position to a table? 3 July 14, 2019
What are some ways that SQL is used in data science? 1 November 5, 2018
Does every SQL statement follow this structure? 3 August 17, 2019
Given a value that is not a unique identifier, can we determine a unique identifier? 1 August 24, 2018
What order are rows selected from a table? 1 November 5, 2018
Can you CROSS JOIN on more than two tables? 1 August 24, 2018
When should we use each type of JOIN? 1 August 24, 2018
Are there guidelines to splitting a table as provided in the example? 4 September 24, 2019
What are some other useful things that SQL lets us do? 5 July 28, 2019