What is the use of on in mysql

The ON clause in MySQL is used to connect multiple tables, and the connection columns in the specified tables must match. The ON clause is used to specify connection conditions and supports connection types such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN. The advantages include reducing data redundancy, improving query efficiency, and enhancing data integrity.

The role of ON in MySQL

The ON clause is used to join two or more tables. It specifies the join condition that the join columns or expressions must match.

Usage

Syntax:

<code class="sql">SELECT *
FROM table1
INNER JOIN table2 ON table1.column = table2.column;</code>

Where:

• table1 and table2 is the table to be connected.
• column is the column to be joined in the two tables.

Types

MySQL supports the following connection types, each with its own ON clause:

• INNER JOIN: Return only rows from both tables that have matching join columns.
• LEFT JOIN: Returns all rows in the first table, even if there are no matching rows in the second table.
• RIGHT JOIN: Returns all rows in the second table, even if there are no matching rows in the first table.
• FULL JOIN: Returns all rows from both tables, even if there are no matching rows.

Advantages

The advantages of using the ON clause include:

• Reduce data redundancy: By joining tables, you avoid storing duplicate data in multiple tables.
• Improve query efficiency: Joining tables can create a virtual table that contains the required columns from multiple tables, thereby reducing the time required for queries.
• Enhance data integrity: Join conditions ensure data consistency between different tables.

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