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 perform a period arithmetic operation on a derived period column, except in a WHERE or ON clause.
A derived period column cannot:
- be projected
- be part of a primary or secondary index
- be specified as part of a PARTITION BY COLUMN clause
- contain column attributes
- Name of the derived period column and cannot match the name of any other column in the table.
- DATE or timestamp column to use as the start of the period.
- DATE or timestamp column to use as the end of the period.
- You can specify UNTIL_CHANGED.