Often parent-child relationships exist between tables. To avoid repeating groups of data stored on one table, a child table is used to store the repeating information. Records on a child table cannot exist without a related parent record. Child tables have identifying relationships with parent tables.
Records on a parent table should be archived or purged along with related records on all child tables. This ensures that child records are not orphaned. This axiom is recursive, as child tables may have child tables of their own.
Suppose that you want to archive meter read data. For each CI_MR (meter read) record that is archived, the related child records in CI_REG_READ (register reading) and CI_MR_REM (meter read remark) tables should also be archived. The following illustrates how register reading records and meter read remark records are related to a parent meter read record.
