mysql on what does it mean

MySQL ON keyword is used to specify join conditions in a JOIN operation to join data from different tables and create complex query results that match or merge records. It can be used with USING (column) or ON ... WHERE ..., the syntax is: SELECT ... FROM table1 JOIN table2 ON table1.column1 = table2.column2.

What is MySQL ON?

The ON keyword in MySQL is used to specify join conditions in a JOIN operation. It can join data from different tables to create more complex and useful query results.

Syntax for the ON keyword

SELECT ...
FROM table1
JOIN table2 ON table1.column1 = table2.column2

In this syntax:

• table1 and table2 is the table to be connected.
• column1 and column2 are the columns used to join the two tables.
• = is a comparison operator used to check whether the values ​​of two columns are equal.

Purpose of the ON keyword

The ON keyword is used to join tables in the following situations:

• Find two or matching records in multiple tables. For example, find customers who purchased a specific product.
• Merge data from different tables into one table. For example, merge customer information with order information.
• Create complex queries involving multiple tables and join conditions.

Alternatives for the ON keyword

The ON keyword can be used with the following alternatives:

• USING (column): Specifies the common column to be used for the join.
• ON ... WHERE ...: Provides more flexible connection conditions and allows the use of additional conditions.

Example

The following query uses the ON keyword to join the Customers table and the Orders table to find customers who purchased a specific product:

SELECT *
FROM Customers
JOIN Orders ON Customers.customer_id = Orders.customer_id
WHERE Orders.product_id = 123;

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