TABLE MANIPULATION

Title: Table Manipulation

Table manipulation in the context of relational databases refers to the actions performed to create, modify, and delete tables, as well as to manage the data within them. Here's an overview of table manipulation:

1. Creating Tables:
   The creation of tables is the first step in organizing data within a relational database. Tables are created using the CREATE TABLE statement in SQL. This statement defines the table's structure, including the column names, data types, and any constraints. For example:

CREATE TABLE employees (

 id INT PRIMARY KEY,

 name VARCHAR(100),

 age INT,

 department_id INT

);

2. Altering Tables:
   Tables can be modified after creation using the ALTER TABLE statement. Common modifications include adding, modifying, or dropping columns, as well as adding or dropping constraints. For example:

ALTER TABLE employees 

ADD COLUMN salary DECIMAL(10, 2);

3. Dropping Tables:
   To delete a table and its associated data from the database, the DROP TABLE statement is used. This action cannot be undone, so it should be used with caution. For example:

DROP TABLE employees;

4. Constraints:
   Constraints are rules that enforce data integrity within tables. Common constraints include primary keys, foreign keys, unique constraints, and not-null constraints. These constraints help maintain the integrity and consistency of the data stored in the tables.

5. Primary Keys:
   A primary key uniquely identifies each record in a table. It ensures that no two records have the same key value, and it is often used as the main reference for relationships with other tables. Primary keys are defined using the PRIMARY KEY constraint.

6. Foreign Keys:
   Foreign keys establish relationships between tables. They ensure referential integrity by enforcing that values in one table's foreign key columns correspond to values in another table's primary key columns. Foreign keys are defined using the FOREIGN KEY constraint.

7. Indexes:
   Indexes are data structures that improve the speed of data retrieval operations by providing quick access to rows based on specific column values. Indexes can be created on one or more columns of a table using the CREATE INDEX statement.

8. Data Manipulation:
   Once tables are created, data manipulation operations such as insertion, updating, deletion, and querying can be performed using SQL's INSERT, UPDATE, DELETE, and SELECT statements, respectively.

9. Normalization:
   Tables can be designed and manipulated to adhere to normalization principles, which help reduce data redundancy and dependency. Normalization involves organizing tables and their relationships to minimize anomalies and improve data integrity.

Table manipulation is a fundamental aspect of working with relational databases. Understanding how to create, modify, and manage tables effectively is essential for designing efficient and scalable database systems.