MySql

A MySQL database (DB) is a structured collection of data organized into tables within the MySQL relational database management system. It uses a SQL-based interface to manage data, making it ideal for applications requiring high performance, reliability, and scalability. Here's a brief overview of how a MySQL database functions:

Structure of a MySQL Database

1. Tables: Each database consists of one or more tables. Tables are the primary structure where data is stored. Each table is defined by a schema, which includes columns and data types.
   • Columns: Each table consists of columns, which define the structure of the data (e.g., id INT, name VARCHAR(100), email VARCHAR(100)).
   • Rows: Tables contain rows, which are individual records of data.
2. Primary Key: A unique identifier for each row in a table.
3. Indexes: Enhance query performance by allowing faster searches.
4. Relationships:
   • Foreign Keys: Create links between tables, ensuring referential integrity.
   • Joins: Used to combine rows from two or more tables based on a related column.
5. Data Types:
   • Numeric (INT, FLOAT, DOUBLE),
   • String (VARCHAR, CHAR, TEXT),
   • Date and Time (DATE, DATETIME, TIMESTAMP),
   • Binary (BLOB).

Managing MySQL Databases

• Creating a Database:
  sql

  CREATE DATABASE my_database_name;
  

• Selecting a Database:
  sql

  USE my_database_name;
  

• Creating a Table:
  sql

  CREATE TABLE users (
      id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
      name VARCHAR(100) NOT NULL,
      email VARCHAR(100) NOT NULL,
      created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
  );
  

• Inserting Data:
  sql

  INSERT INTO users (name, email) VALUES ('John Doe', '[email protected]');
  

• Selecting Data:
  sql

  SELECT * FROM users WHERE id = 1;
  

• Updating Data:
  sql

  UPDATE users SET email = '[email protected]' WHERE id = 1;
  

• Deleting Data:
  sql

  DELETE FROM users WHERE id = 1;
  

Advanced Features

1. Indexes:
   • CREATE INDEX idx_email ON users (email);
2. Joins:
   • SELECT u.name, o.order_id FROM users u INNER JOIN orders o ON u.id = o.user_id;
3. Transactions:
   • BEGIN;, COMMIT;, ROLLBACK; for ensuring data consistency.
4. Stored Procedures:
   • Encapsulate complex operations.
   • sql

     DELIMITER //
     CREATE PROCEDURE get_user_info(IN user_id INT)
     BEGIN
         SELECT * FROM users WHERE id = user_id;
     END//
     DELIMITER ;
     

5. Views:
   • Virtual tables representing a SELECT query.
   • sql

     CREATE VIEW user_orders AS
     SELECT u.name, o.order_id
     FROM users u
     INNER JOIN orders o ON u.id = o.user_id;