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FOREIGN KEY Constraint in Oracle

• FOREIGN KEY is a referential integrity constraint.
• It establishes a relationship between PRIMARY KEY or UNIQUE of the same table or a different table
• It can be created on a single column or it can

PRIMARY KEY Constraint in Oracle

• The PRIMARY KEY enforces the uniqueness in table.
• PRIMARY KEY can be created on a single column or multiple columns (composite key)
• A table can have only one PRIMARY KEY
• PRIMARY KEY can not have

UNIQUE Constraint in Oracle

An UNIQUE constraint specified that a column or a group of columns on which its defined should be unique.
There will be no duplicate value allows in unique key columns.

Types of UNIQUE Constraints:

• SINGLE COLUMN

NOT NULL Constraint in Oracle

Constraints in Oracle

• Constraints allows Oracle to set some rule at table or column level
• It restricts us to do DML operations if there is any dependency in data

Types of constraints:

• NOT NULL
• UNIQUE