Question

Explain what is meant by referntial integrity.how does oracle maintain this in the baseoption table?give reference to the syntax used to set it up and the actions oracle takes to maintain it.

Answer 1

Referential integrity constraint is that that depends on the parent and kid relationship.

During this one in all the columns have the first key constraint and one in all the column of another table have the foreign key constraint.

Therefore you cannot delete the column price that having the foreign key constraint till you ne'er delete its connected primary key column price from parent table.

If you tried to try to this it'll show you error associated with denotative integrity constraint. however if you continue to wish to delete price from kid table however ne'er wish to delete parent table column price then that purpose you'll be able to use 'on delete cascade' possibility.

A denotative integrity rule could be a rule outlined on a key   in one table that guarantees that the values therein key match the values during a key during a connected table.

Referential integrity additionally includes the principles that dictate what varieties of information manipulation are allowed on documented values and the way these actions have an effect on dependent values. The principles related to denotative integrity are:

• Restrict: Disallows the update or deletion of documented information.

• set to Null: once documented information is updated or deleted, all associated dependent information is ready to NULL.

• Set to Default: once documented information is updated or deleted, all associated dependent information is ready to a default price.

• Cascade: once documented information is updated, all associated dependent information is correspondingly updated. Once a documented row is deleted, all associated dependent rows ar deleted.

• No Action: Disallows the update or deletion of documented information. This differs from limit therein it's checked at the tip of the statement, or at the tip of the dealing if the constraint is postponed. Oracle uses No Action as its default action.

Oracle uses integrity constraints to stop invalid information entry into the bottom tables of the info. You’ll be able to outline integrity constraints to enforce the business rules you would like to go along with the data during a info.

If associate degree of the results of a DML statement execution violates an integrity constraint, then Oracle rolls back the statement and returns a blunder.