DBMS :- Referential integrity constraints

Question

select the correct statement from the following on referential integrity

Select one:

a. referential integrity constraints check whether the primary key, values are unique

b. referential integrity constraints check whether an attribute values lies in the given range

c. referential integrity constraints are specified between two relations in a schema

d. referential integrity constraints are specified between entities having recursive relationship

Comments

Is it option D?

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Isn't c more strong answer? D will be some specific case.

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Due to D option, I haven't choose C.  Referential can be specified in same table also and that's what recursive self referential integrity.

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But d is also not always true.If i join two different tables.Self referential also forms binary relationship with both tables same.So indirectly it also joins two tables(although both are same)

Answer 1

Answer : C - referential integrity constraints are specified between two relations in a schema.

Referential integrity constraint example : Foreign key relation. And those two relations can refer to the same relation. This constraint is used to specify that the range of values that an attribute can take depends on the referenced key(Primary key) of the relation. It can take NULL values.

Answer 2

Ans is C, referential integrity constraints are specified between two relations in a schema

Whenever two tables contain one or more common columns, RDBMS can enforce the relationship between the two tables through a referential integrity constraint. Define a PRIMARY or UNIQUE key constraint on the column in the parent table (the one that has the complete set of column values). Define a FOREIGN KEY constraint on the column in the child table (the one whose values must refer to existing values in the other table).

For more references, please refer to the link https://docs.oracle.com/cd/B10500_01/appdev.920/a96590/adg05itg.htm

Answer 3

both c) and d) are correct