JOIN #

Combine multiple tables together. JOIN is typically an INNER JOIN, where results only include matches across both tables. Non-matches are excluded.

SELECT <table_1>.<field>, <table_2>.<field>
FROM <table_1>
JOIN <table 2>
ON <table_1>.<field> = <table_2>.<field>;

LEFT JOINS #

Keeps all the records from the first (left) table, regardless of match.

SELECT ...
FROM <table_1>
LEFT JOIN <table_2>
ON <table_1>.<field> = <table_2>.<field>;

CROSS JOIN #

Combine all rows across multiple tables (i.e., all possible combinations).

This often explodes.

Note there’s no ON statement.

SELECT <table_1>.<field>, <table_2>.<field>
FROM <table_1>
CROSS JOIN <table_2>;