Language reference

MONTH (extract month)

Syntax

MONTH(<date-or-timestamp>)

γ MONTH(order_date) → mo, SUM(amount) → revenue (Orders)

Description

MONTH pulls the month number (1–12) out of a date or timestamp. Use it to group or filter by month — monthly reports, seasonal patterns, "everything in December".

Technical Description

MONTH(d) → NUMBER (1–12). Accepts a DATE or TIMESTAMP (read at UTC); other types are an evaluation error. NULL input returns NULL. PURE, DETERMINISTIC.

Examples

Monthly revenue within a year:

γ MONTH(order_date) → mo, SUM(amount) → revenue
  (σ YEAR(order_date) = 2026 (Orders))

GROUP MONTH(order_date) -> mo, SUM(amount) -> revenue
  (SELECT YEAR(order_date) = 2026 (Orders))

December records:

σ MONTH(event_date) = 12 (Calendar)

SELECT MONTH(event_date) = 12 (Calendar)

Pushdown

SQL: folds to EXTRACT(MONTH FROM <col>) on every dialect but SQLite, which has no date type to extract from. On SQL Server, which has no EXTRACT, it is DATEPART(MONTH, SWITCHOFFSET(<col>, '+00:00')) — the value switched to UTC first, so a DATETIMEOFFSET is read at UTC as the engine reads it. MongoDB: folds to {"$month": "$<col>"} inside a $project stage (requires alias).

Limitations

Argument must be a DATE or TIMESTAMP. Returns 1–12. TIMESTAMP at UTC. NULL in → NULL out.