A temporal database supports multiple version of rows. Dealing with multiple versions can be quite complicated. A number of DBMS vendors have added support for temporal support.

As an example of a valid-time table consider the emp is shown below.

Name	Dept	VTS	VTE
Karen	RD	10	20
Karen	HR	20	30
Søren	RD	15	45

The content of the table emp can be explained as follows.

• In the interval [10, 20) Karen was in the RD department
• At time 20 Karen moved to the HR department and is there until time 30
• Søren is with the RD department in the interval [15, 45)

To create this table the following SQL command are created.

-- create the table
create table emp(
    name varchar(50) not null,
    dept varchar(50) not null,
    vts  integer     not null,
    vte  integer     not null);

-- Insert the data
insert into emp values('Karen', 'RD', 10, 20);
insert into emp values('Karen', 'HR', 20, 30);