Database / SQLite Interview questions
How do you perform a JOIN in SQLite?
SQLite supports the standard SQL join types — INNER JOIN, LEFT JOIN, and
(more recently) RIGHT JOIN and FULL JOIN — combining rows from two or more
tables based on a matching condition.
SELECT person.name, order_item.total FROM person INNER JOIN order_item ON person.id = order_item.person_id; SELECT person.name, order_item.total FROM person LEFT JOIN order_item ON person.id = order_item.person_id; -- includes every person, even those with no matching order_item rows
INNER JOIN only returns rows where a match exists on both sides; LEFT JOIN
returns every row from the left table regardless of whether a match exists, filling in NULLs for
the right side's columns when there's no match — the same standard join semantics used across virtually
every relational database.
What does INNER JOIN return that LEFT JOIN might not?
What value fills in unmatched right-side columns in a LEFT JOIN?
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