| Term | Definition |
|---|---|
| Child Table | A table where the referential constraints are defined. Child table and referencing table are synonyms. |
| Parent Table | The table referenced by a child table. Parent table and referenced table are synonyms. |
| Primary Key UNIQUE Alternate Key |
A unique identifier for a row of a table. |
| Foreign Key | A column set in the child table that is also the primary key (or a UNIQUE alternate key) in the parent table. Foreign keys can consist of as many as 64 different columns. |
| Referential Constraint | A constraint defined on a column set or a table to ensure referential integrity. For example, consider the following table definition: CREATE TABLE A (A1 CHAR(10) REFERENCES B (B1), /* 1 */ A2 INTEGER FOREIGN KEY (A1,A2) REFERENCES C /* 2 */ PRIMARY INDEX (A1)); This CREATE TABLE statement specifies the following referential integrity constraints.
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