Which of the following is not an integrity constraint?
A. not null
D. check ‘predicate’
The Correct Answer Is:
- D. check ‘predicate’
Answer Explanation for Question ” Which of the following is not an integrity constraint?”
In order to maintain the quality of information, integrity constraints are used. During the data insertion, updating, and other processes, integrity constraints ensure that the data integrity is not compromised. The integrity constraint protects the database from accidental damage.A certain set of rules is used in database management systems (DBMS) to maintain the quality and consistency of data. These integrity constraints ensure that data integrity is maintained whenever a record is inserted, deleted, or updated in the database, thus protecting it from accidental damage.
Integrity constraints in DBMSs can be divided into four types:
- Domain Constraint
- Entity Constraint
- Referential Integrity Constraint
- Key Constraint
a) Domain Integrity Constraint
In a database, a domain integrity constraint restricts what attributes or values can be stored in a column or relation. We can specify whether a column can hold null values or not, whether the values need to be unique, what types or sizes of values can be entered in the column, and what default values can be used.
b) Entity Integrity Constraint
In data tables, Entity Integrity Constraints ensure that each row or record is unique. UNIQUE constraint and PRIMARY KEY constraint are the two types of integrity constraints that ensure the uniqueness of each row. Data tables use unique keys to identify records. As both of them ensure the uniqueness of a record, it can be considered somewhat similar to the Primary Key. It can be used on more than one column of a data table, unlike a primary key which cannot accept NULL values.
c) Referential Integrity Constraint
In order for two tables to have a valid relationship, a Referential Integrity Constraint must exist. By doing this, it will ensure that if there is a foreign key in a table relationship, it will always refer to a corresponding value in the second table, or it will be null.
d) Key Constraints
In SQL, there are a number of key constraints that ensure entity or record identification in the database is unique or different. It is possible to have more than one primary key in a table, but only one can be the primary key.There are several key constraints in SQL, including:
- Primary Key Constraint
- Foreign Key Constraint
- Unique Key Constraint