The DAYOF function returns an INTEGER
in the range of 1 through 7, giving the day of the week on which a specified date falls. A result of 1
refers to Sunday. The result has the same dimensions as the specified DATE expression.
An expression that has the DATE data type, or a text expression that specifies a date. Instead of a DATE expression, you can specify a text expression that has values that conform to a valid input style for dates. DAYOF automatically converts the values of the text expression to DATE values, using the current setting of the DATEORDER option to resolve any ambiguity.