Language reference

DOW (day of week, Sunday 0)

Syntax

DOW(<date-or-timestamp>)

γ DOW(order_date) → weekday, COUNT(*) → orders (Orders)

Description

DOW gives the day of the week as a number, Sunday 0 through Saturday 6, the way PostgreSQL's EXTRACT(DOW …) counts. Use it to compare weekdays with weekends or to see which day of the week is busiest.

Technical Description

DOW(d) → NUMBER, 0 (Sunday) to 6 (Saturday). It is EXTRACT(DOW FROM d). Accepts a DATE or TIMESTAMP (a TIMESTAMP is read at UTC); other types are an evaluation error. NULL input returns NULL. PURE, DETERMINISTIC.

Examples

Weekend orders:

σ DOW(order_date) = 0 ∨ DOW(order_date) = 6 (Orders)

SELECT DOW(order_date) = 0 OR DOW(order_date) = 6 (Orders)

Pushdown

SQL: EXTRACT(DOW FROM <col>) on PostgreSQL and DuckDB, and DAYOFWEEK(<col>) - 1 on MySQL, whose count starts at Sunday = 1. SQL Server's weekday depends on the session's DATEFIRST, so there it runs in the engine, as on SQLite and Db2. MongoDB: $dayOfWeek less one.

Limitations

Sunday is 0. For a week that starts on Monday, ISODOW counts Monday 1 to Sunday 7. MySQL's DAYOFWEEK counts Sunday as 1, so it is not offered under that name.