A derived period column.
A DATE or timestamp column can be part of only one derived period column definition and can only be used as the start of the period or end of the period, not both. The data type of begin and end columns in a derived period column must match, including the same properties, the same DATE or timestamp data type, and identical format column attribute.
A table can have more than one derived period column. For each derived period column you add, the maximum limit of 2048 non-derived period columns is reduced by one. You cannot change the NOT NULL attribute, if specified, of the begin and end columns in a derived period column.
A derived period column can only include a period arithmetic operation in a WHERE or ON clause.
A derived period column cannot be:
- Part of a primary or secondary index
- Specified as part of a PARTITION BY COLUMN clause
- Name of the derived period column. period_name cannot match the name of any other column in the table.
- The DATE or timestamp column to use as the start of the period.
- The DATE or timestamp column to use as the end of the period.
- You can specify UNTIL_CHANGED.