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Entity Integrity Rule in RDBMS
For Entity Integrity Rule, each table has a Primary Key.
Primary Key cannot have NULL value.
Above, you can see our primary key is Student_ID. We cannot consider Student_Awards as the primary key since not every student would have received the award.
Let us see another example −
In the above table, the Primary Key is Employee_ID
Let us now summarize the Entity Integrity Rule −
- Make sure that each tuple in a table is unique.
- Every table mush has a primary key, for example, Student_ID for a Student table.
- Every entity is unique.
- The relations Primary Key must have unique values for each row.
- Primary Key cannot have NULL value and must be unique.
- Example can be an Employee_ID cannot be null in an Employee table.
- Referential Integrity Rule in RDBMS
- Difference between Strong Entity and Weak Entity
- Explain difference between Strong Entity and Weak Entity
- Explain the concept of integrity in DB2 along with types of integrity
- RDBMS terminologies
- Composite Key in RDBMS
- Secondary Key in RDBMS
- Super Key in RDBMS
- Surrogate Key in RDBMS
- Candidate Key in RDBMS
- Alternate Key in RDBMS
- Foreign Key in RDBMS
- Unique Key in RDBMS
- Entity-Relationship Diagram
- Identifying Entity Relationships in DBMS