explain abat different type of constraints

Shyamala, your question is not very clear but in case you are asking about the 7 types of constraints in DBMS or Database Management System in Computer Science, I have mentioned them below:

• Not Null- It ensures that the corresponding column cannot have a null value.
• Unique- It ensures that all the entries in the column are unique.
• Primary Key- It is a combination of Not Null and Unique. It is used to uniquely identify a row/ tuple in a table.
• Foreign Key- It references the Primary Key and uniquely identifies a row in another table.
• Check- It ensures that all values in a column satisfy a specific condition.
• Default- It sets a default value for a column when no value is specified.
• Index- It is used to create and retrieve data from the database quickly.