A derived period column is derived from DateTime data in other table columns. Derived period columns can be specified in a table definition and are maintained dynamically by the database.
ANSI temporal tables can have one or two derived period columns to represent different kinds of time. These derived period columns combine the values from two regular DateTime type columns, and represent the period or duration bounded by the values in the two component columns. Special SQL DDL syntax for CREATE and ALTER TABLE statements allows specification of these derived period columns to create temporal tables.
Note: The period that a derived period column represents starts at the beginning bound and extends up to, but does not include, the ending bound value.
Derived period columns function much like native Teradata Database Period data type columns. Period data types are not ANSI compatible, they are Teradata extensions to the ANSI SQL:2011 standard. Teradata Database provides rich support for Period data types, including functions, operators, and predicates, many of which can be used on derived temporal columns. Period functions BEGIN, END, LAST, and INTERVAL, and the period predicate operator MEETS are not ANSI standard SQL.