The document outlines various integrity constraints in a Database Management System (DBMS) to ensure data accuracy and prevent invalid entries. It describes primary key, foreign key, unique key, default, not null, and check constraints, along with their syntax and examples. These constraints help maintain the reliability and integrity of data across database tables.

1. Integrity Constraints in DBMS
Mrs. Pallavi Patil

2. Data integrity constraints
• Integrity means correctness and completeness of data. Constraints
means restriction.
• Integrity constraints means the mechanism used to prevent invalid
data entry into table.
Mrs. Pallavi Patil

3. i. Primary key constraint
 It prevents duplication of data values within column and also does not
allow null valuse.
Syntax:
Create table table_name(column_name datatype (size) primary key);
Ex. Create table Student(Rollno number(5) primary key, Stud_name
varchar2(20), marks number(4,2));
ii. Foreign key constraint
• also called referential integrity constraint.
• Develops parent-child relationship between two tables.
• value of foreign key is derived from primary key of parent table.
Mrs. Pallavi Patil

4. • Primary key is present in parent table and foreign key is present in child
table.
Syntax:
Create table table_name( column_name datatype (size), foreign
key(column_name) references parent table_name(column_name));
Ex.
Create table department( empno number (5), foreign key(emp_number)
references emp(emp_no));
Mrs. Pallavi Patil

5. Unique key constraint
• It is used to prevent duplicate data entry within specified column.
• It allows null values.
Syntax:
Create table table_name(ColumnName datatype(size) unique);
Create table Student(Rollno number(5) unique, Stud_name varchar2(20));
Mrs. Pallavi Patil

6. Default constraint
• It is used to assign default value to the column.
• The default value is added to all new records if no other value is
specified.
Ex. Create table Student(Rollno number(5) , Stud_name
varchar2(20), stud_city varchar( 15) default ‘sangli’);
Mrs. Pallavi Patil

7. Not null constraint
• By default all columns allow null values, but when not null constraint is
enforced for the column, then that column does not allow null values.
Syntax:
Create table tableName(column_name datatype(size) not null);
Ex. Create table Student(Rollno number(5) , Stud_name varchar2(20) not
null);
Check constraint
• These constraints defines the condition that each row must satisfied.
• Single column can have multiple check constraints.
Mrs. Pallavi Patil

8. Syntax
Create table table_name(column_name datatype(size) check(condition));
Ex.
Create table Student(Rollno number(5), Stud_name varchar2(20), marks
number(4,2) check(marks > 40));
Mrs. Pallavi Patil