In a Database Management System (DBMS), various objects are used to organize, manage, and retrieve data efficiently. These objects play crucial roles in maintaining the integrity and performance of databases. Here’s a detailed explanation of the most common database objects:

1. Tables

Tables are the primary storage units for data in a database. Data is stored in rows and columns, with each row representing a record and each column representing an attribute or field.

• Example: In a "Students" table, columns might include Student_ID, Name, and Age. Each row contains data for individual students like 101, Thirdy, 20.

Features of Tables:

• Every table has a primary key that uniquely identifies each record.

• Tables allow for structured data storage and easy querying.

2. Views

A view is a virtual table based on the result of a SQL query. It does not store data itself but presents data from one or more tables. Views help simplify complex queries and limit access to certain data.

• Example: A view could show only the Name and Department of employees, hiding sensitive columns like Salary.

Features of Views:

• They help simplify data presentation.

• Views can control access to specific data for different users.

3. Indexes

Indexes are used to speed up data retrieval. They function like an index in a book, allowing the database to quickly find records without scanning every row in a table.

• Example: An index on the Student_ID column can quickly retrieve specific students from a large table.

Features of Indexes:

• They optimize SELECT queries.

• Indexes can slow down data insertion and updates because the index also needs to be updated.

4. Sequences

A sequence generates unique numbers, often used for primary keys. Sequences ensure that every new record has a unique identifier.

• Example: In a "Students" table, a sequence can generate a new unique Student_ID for each new student.

Features of Sequences:

• Sequences are used to auto-generate unique numbers.

• They are independent objects in the database.

5. Stored Procedures

A stored procedure is a set of SQL statements stored in the database. These can be executed to perform operations like data insertion, updates, or deletions.

• Example: A stored procedure might automate the process of adding a new student and assigning them to classes.

Features of Stored Procedures:

• They can automate repetitive tasks.

• Stored procedures can accept input parameters and return results.

6. Triggers

A trigger is a type of stored procedure that automatically executes in response to certain events, such as when data is inserted, updated, or deleted in a table.

• Example: A trigger could update a LastModified column whenever a row in a table is updated.

Key Features of Triggers:

• They enforce business rules by automating certain tasks.

• Triggers help maintain data integrity by ensuring specific actions occur automatically when certain events happen.

7. Functions

A function is similar to a stored procedure, but it returns a single value. Functions are often used to perform calculations or format data.

• Example: A function could calculate a student's average score across multiple exams.

Features of Functions:

• Functions return a value and can be used within SQL queries.

• They simplify complex calculations and operations.

8. Constraints

Constraints are rules applied to table columns to ensure data integrity. They prevent invalid data from being entered.

• Common Constraints Include:

  • Primary Key (PK): Ensures each row has a unique identifier.

  • Foreign Key (FK): Ensures referential integrity by linking two tables.

  • Unique: Ensures that no duplicate values are entered in a column.

  • Not Null: Ensures that a column cannot be left empty.

  • Check: Ensures that data in a column meets specified conditions.

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Database objects are essential for organizing and managing data in a DBMS. Tables store data, views simplify data access, indexes improve query speed, and constraints ensure data integrity. Stored procedures, functions, triggers, and sequences further automate and optimize database operations, making it easier to manage complex systems.

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References

1. GeeksforGeeks - Database Objects in DBMS
   GeeksforGeeks

2. InformIT - Managing Database Objects in SQL
   InformIT

3. Oracle Documentation - Database Objects
   Oracle Docs​(Oracle)

4. MS SQL Tips - SQL Server Stored Procedures, Views, and Functions
   MSSQL Tips

5. TutorialsPoint - DBMS Database Objects
   TutorialsPoint​