Database Fundamentals
Everything on SkillVeris tagged Database Fundamentals — collected across the glossary, study notes, blog, and cheat sheets.
5 resources across 1 library
Interview Questions(5)
UNION vs UNION ALL: What is the Difference?
UNION combines the result sets of two or more SELECT queries and removes duplicate rows, while UNION ALL combines them and keeps every row, including duplicate…
What are the INTERSECT and EXCEPT Operators in SQL?
INTERSECT returns only the rows that appear in both of two SELECT result sets, while EXCEPT (also called MINUS in some databases) returns the rows from the fir…
What is a Self-Join and When Would You Use One?
A self-join is a regular join where a table is joined with itself, typically by giving the table two different aliases so rows can be compared against other ro…
What is a CROSS JOIN and When is it Useful?
A CROSS JOIN produces the Cartesian product of two tables, pairing every row from the first table with every row from the second table, with no join condition…
What is the Difference Between a Semi-Join and an Anti-Join?
A semi-join returns rows from the first table that have at least one matching row in the second table, without duplicating rows or pulling in any columns from…