WEEKDAY

WEEKDAY(date, return_type=None)

Returns the day of the week for a given date, using a customizable numbering scheme.

This function calculates the weekday for each date in date or a single date. The numbering of the days is determined by return_type, following conventions similar to Excel’s WEEKDAY function.

Parameters:

• date (Operand) – The date or date array to evaluate.

• return_type (Operand | int | None) – Optional parameter specifying the day numbering scheme. Can be a scalar integer (1-3 or 11-17) or a numeric model object. Defaults to 1 (Sunday=1 through Saturday=7).

Return type:

Formula

Returns:

A formula representing the weekday(s).

Raises:

ValueError – If date is not DATE or DATE_ARRAY, or if return_type is outside the allowed range or of invalid type and is determinable at compile time.

Examples

Default numbering (Sunday=1 through Saturday=7):

WEEKDAY(DATE("2025-09-03"))
# Returns 4 (Wednesday)

Monday=1 through Sunday=7:

WEEKDAY(DATE("2025-09-03"), 2)
# Returns 3 (Wednesday)

Monday=0 through Sunday=6:

WEEKDAY(DATE("2025-09-03"), 3)
# Returns 2 (Wednesday)

Note

• The return type follows the same format as Excel’s WEEKDAY function. For details see: <https://support.microsoft.com/en-us/office/ weekday-function-60e44483-2ed1-439f-8bd0-e404c190949a>

``date`` — accepted types

• DATE

• DATETIME

• DATETIME_ARRAY

• DATE_ARRAY

``return_type`` (optional) — accepted types

• DECIMAL

• DECIMAL_ARRAY

• INTEGER

• INTEGER_ARRAY

Return types

• INTEGER

• INTEGER_ARRAY