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Constraints and Database Schemas Video Lecture | SSC CGL Tier 2 - Study Material, Online Tests, Previous Year

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FAQs on Constraints and Database Schemas Video Lecture - SSC CGL Tier 2 - Study Material, Online Tests, Previous Year

1. What are constraints in a database schema?
Ans. Constraints in a database schema are rules or conditions that are imposed on the data stored in a database. They ensure that the data follows certain criteria or relationships, maintaining the integrity and consistency of the database. Constraints can include rules such as unique values, primary key constraints, foreign key constraints, and check constraints.
2. How do constraints help in maintaining data integrity?
Ans. Constraints play a crucial role in maintaining data integrity in a database. They enforce rules and conditions on the data, preventing it from being inserted, updated, or deleted in a way that violates the defined criteria. Constraints such as unique constraints ensure that each value in a column is unique, while foreign key constraints maintain referential integrity by enforcing relationships between tables.
3. What is the difference between primary key and foreign key constraints?
Ans. A primary key constraint is used to uniquely identify each record in a table. It ensures that the values in the specified column(s) are unique and cannot be null. On the other hand, a foreign key constraint establishes a relationship between two tables. It enforces referential integrity by ensuring that the values in a column of one table match the values in another table's primary key column.
4. How do check constraints work in a database schema?
Ans. Check constraints allow the definition of conditions that the data must meet before being inserted or updated in a table. These conditions can be based on logical expressions, comparisons, or patterns. Check constraints are used to restrict the values that can be stored in a column, ensuring that they meet specific criteria.
5. Can constraints be modified or dropped after they are created?
Ans. Yes, constraints can be modified or dropped after they are created. In most database management systems, there are commands or statements available to alter or drop constraints. However, it is important to consider the impact of modifying or dropping constraints on the data integrity and consistency of the database. It is recommended to carefully evaluate and plan any changes to constraints before implementing them.
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