-20491   INVALID SPECIFICATION OF PERIOD period-name. REASON CODE = reason-code.

The specification of an attribute in a CREATE or ALTER statement for a period is invalid.

period-name

The period that contains the invalid specification.

reason-code

A numeric value that indicates why the attribute might be invalid:

1

The start column name must not be the same as the end column name for the period.

2

The name of a column in a period must not be the same as a column used in the definition of another period for the table.

3

The data type, length, precision, and scale for the start column must be the same as for the end column.

5

For a BUSINESS_TIME period, the column must not be a column defined with a GENERATED clause.

6

For a SYSTEM_TIME period, the attributes of the start column and end column must be one of the combinations:

• The start column definition is GENERATED ALWAYS AS ROW BEGIN and the end column definition is GENERATED ALWAYS AS ROW END.
• The start column definition is GENERATED BY DEFAULT AS ROW BEGIN and the end column definition is GENERATED BY DEFAULT AS ROW END.