Which action needs to be performed in order to complete the definition of an
application-period temporal table?
A.
A history table must be defined and associated with the base table.
B.
A BUSINESS_TIME period must be specified in a CREATE or ALTER of the table.
C.
A transaction-start-id column must be defined for the table.
D.
A unique index must be created that prevents overlapping of the BUSINESS_TIME
period of the table.
BUSINESS_TIME period
The BUSINESS_TIME period columns for an application-period temporal table record when the version of a row is valid from a user or business application perspective.
Example
This section contains more examples of creating application-period temporal tables.
Changing an existing table into an application-period temporal table
The following example adds time columns and a BUSINESS_TIME period to an existing table (employees) enabling application-period temporal table functionality. Adding the BUSINESS_TIME WITHOUT OVERLAPS clause ensures that an employee is listed only once in any time period.
ALTER TABLE employees ADD COLUMN bus_start DATE NOT NULL;
ALTER TABLE employees ADD COLUMN bus_end DATE NOT NULL;
ALTER TABLE employees ADD PERIOD BUSINESS_TIME(bus_start, bus_end);
ALTER TABLE employees ADD CONSTRAINT uniq
UNIQUE(employee_id, BUSINESS_TIME WITHOUT OVERLAPS);
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