MySql DB

MySql

Last modified on: March 25, 2025

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<p>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:</p>
<h3>Structure of a MySQL Database</h3>
<ol>
<li><strong>Tables</strong>: 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.
<ul>
<li><strong>Columns</strong>: Each table consists of columns, which define the structure of the data (e.g., <code>id INT</code>, <code>name VARCHAR(100)</code>, <code>email VARCHAR(100)</code>).</li>
<li><strong>Rows</strong>: Tables contain rows, which are individual records of data.</li>
</ul>
</li>
<li><strong>Primary Key</strong>: A unique identifier for each row in a table.</li>
<li><strong>Indexes</strong>: Enhance query performance by allowing faster searches.</li>
<li><strong>Relationships</strong>:
<ul>
<li><strong>Foreign Keys</strong>: Create links between tables, ensuring referential integrity.</li>
<li><strong>Joins</strong>: Used to combine rows from two or more tables based on a related column.</li>
</ul>
</li>
<li><strong>Data Types</strong>:
<ul>
<li>Numeric (<code>INT</code>, <code>FLOAT</code>, <code>DOUBLE</code>),</li>
<li>String (<code>VARCHAR</code>, <code>CHAR</code>, <code>TEXT</code>),</li>
<li>Date and Time (<code>DATE</code>, <code>DATETIME</code>, <code>TIMESTAMP</code>),</li>
<li>Binary (<code>BLOB</code>).</li>
</ul>
</li>
</ol>
<h3>Managing MySQL Databases</h3>
<ul>
<li><strong>Creating a Database</strong>:
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<pre class="language-php"><code>CREATE DATABASE my_database_name;
</code></pre>
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</li>
<li><strong>Selecting a Database</strong>:
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<pre class="language-php"><code>USE my_database_name;
</code></pre>
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</li>
<li><strong>Creating a Table</strong>:
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<pre class="language-php"><code>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
);
</code></pre>
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</li>
<li><strong>Inserting Data</strong>:
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<pre class="language-php"><code>INSERT INTO users (name, email) VALUES ('John Doe', 'john@example.com');
</code></pre>
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</li>
<li><strong>Selecting Data</strong>:
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<pre class="language-php"><code>SELECT * FROM users WHERE id = 1;
</code></pre>
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</li>
<li><strong>Updating Data</strong>:
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<pre class="language-php"><code>UPDATE users SET email = 'newemail@example.com' WHERE id = 1;
</code></pre>
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</li>
<li><strong>Deleting Data</strong>:
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<pre class="language-php"><code>DELETE FROM users WHERE id = 1;
</code></pre>
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</li>
</ul>
<h3>Advanced Features</h3>
<ol>
<li><strong>Indexes</strong>:
<ul>
<li><code>CREATE INDEX idx_email ON users (email);</code></li>
</ul>
</li>
<li><strong>Joins</strong>:
<ul>
<li><code>SELECT u.name, o.order_id FROM users u INNER JOIN orders o ON u.id = o.user_id;</code></li>
</ul>
</li>
<li><strong>Transactions</strong>:
<ul>
<li><code>BEGIN;</code>, <code>COMMIT;</code>, <code>ROLLBACK;</code> for ensuring data consistency.</li>
</ul>
</li>
<li><strong>Stored Procedures</strong>:
<ul>
<li>Encapsulate complex operations.</li>
<li>
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<pre class="language-php"><code>DELIMITER //
CREATE PROCEDURE get_user_info(IN user_id INT)
BEGIN
    SELECT * FROM users WHERE id = user_id;
END//
DELIMITER ;
</code></pre>
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</li>
</ul>
</li>
<li><strong>Views</strong>:
<ul>
<li>Virtual tables representing a SELECT query.</li>
<li>
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<pre class="language-php"><code>CREATE VIEW user_orders AS
SELECT u.name, o.order_id
FROM users u
INNER JOIN orders o ON u.id = o.user_id;
</code></pre>
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</li>
</ul>
</li>
</ol>
<h3>&nbsp;</h3>
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