E0021 missing-join-condition

Tables in FROM with no condition linking them.

What it reports

A table in a comma-separated FROM list that nothing links with the other tables: no WHERE condition references it together with another table. Every row is combined with every row of the others (a cross join), which multiplies the result and is usually a forgotten join condition.

Example

SELECT u.name, o.total FROM users u, orders o;

warning[E0021]: No condition links 'o' with the other tables: every row is joined with every row (cross join)
  --> q.sql:1:38
    |
  1 | SELECT u.name, o.total FROM users u, orders o;
    |                                      ^^^^^^
    = help: Add a join condition for 'o' to WHERE, or write CROSS JOIN if every combination is intended

Fixed:

SELECT u.name, o.total FROM users u, orders o WHERE o.user_id = u.id;

Notes

Explicit joins (CROSS JOIN, JOIN ... ON) are never reported. To keep deliberate cross joins quiet, nothing is reported when:

• a WHERE condition filters one of the tables on its own (WHERE t.name = 'rust': every row combined with the chosen ones),
• the other item is a CTE, a subquery or a table function (it may return a single row), or refers to an earlier table (LATERAL, unnest(u.tags), BigQuery u.tags),
• the statement has template tags (they may add conditions), or a condition uses a column sqlsift can't attribute to one table.

A condition that references several tables links all of them, also inside OR or a subquery.

Configuring

# sqlsift.toml
[rules]
missing-join-condition = "error"   # or "off"

Or for a single line: -- sqlsift:disable E0021. The examples use the schema on the Rules page.