extend

Adjusts the precision of a datetime or date expression. The expression cannot be a quoted string representation of a date value. If you do not specify first and last qualifiers, the default qualifiers are year to fraction (3). If the expression contains fields that are not specified by the qualifiers, the unwanted fields are discarded. If the first qualifier specifies a larger (more significant) field than what exists in the expression, the new fields are filled in with values returned by the current function. If the last qualifier specifies a smaller (less significant) field than what exists in the expression, the new fields are filled in with constant values. A missing month or day field is filled in with 1, and missing hour to fraction fields are filled in with 0.

extend ( date_expression , ' { ' year to second ' } ' )

extend ( some_date_column , { year to second } )