What does on mean in mysql

In MySQL, ON is used to connect tables, and the connection condition is the comparison of columns between tables. It is different from WHERE, which is used to filter query results.

The meaning of ON in MySQL

In MySQL, ON is a keyword used to connect tables and Specify connection conditions. It is used to define relationships between tables in SQL queries.

How to use ON

The ON keyword is followed by a join condition that specifies how to join the two tables together. The join condition is usually an equality or inequality that compares the columns of the two tables.

For example, the following query uses the ON keyword to join the students table and the scores table:

<code>SELECT *
FROM students
INNER JOIN scores ON students.id = scores.student_id;</code>

In this query, the ON keyword is followed by a The connection condition students.id = scores.student_id, which specifies that the basis for joining the two tables is the id column.

The difference between ON and WHERE

The ON and WHERE keywords may seem similar, but have different functions. ON is used to join tables, while WHERE is used to filter results.

The ON keyword is used to specify the conditions for table joins, and the WHERE keyword is used to specify the rows returned in the query.

For example, the following query uses the WHERE keyword to filter results in the students table:

<code>SELECT *
FROM students
WHERE name = 'John';</code>

In this query, the WHERE keyword is followed by a condition name = 'John', which specifies that only rows whose name column equals John are returned.

Conclusion

ON is a powerful keyword in MySQL that is used to join tables and specify join conditions. By using ON correctly, you can extract data from multiple tables and create meaningful relationships.

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