FROM - MySQL Clauses

In MySQL, the FROM clause is used to specify the tables from which you want to select data. This clause is required for any SELECT statement that retrieves data from a specific table or tables. In this tutorial, we'll discuss how to use the FROM clause in MySQL.

Syntax

The basic syntax for the FROM clause in MySQL is as follows:

SELECT column1, column2, ...
FROM table1, table2, ...
WHERE condition;

The FROM clause is used to list the tables from which you want to retrieve data. Multiple tables can be listed in the FROM clause, separated by a comma. You can then select specific columns from these tables using the SELECT statement, and filter the results using the WHERE clause.

Example

Let's say we have a database with two tables: customers and orders. We want to retrieve a list of all customers and their orders. Here's how we can use the FROM clause in MySQL:

SELECT customers.*, orders.*
FROM customers, orders
WHERE customers.id = orders.customer_id;

In this example, we used the FROM clause to list both the customers and orders tables. We then used the SELECT statement to retrieve all columns from both tables using the .* wildcard. Finally, we joined these tables using the WHERE clause to get only those rows where the id from the customers table matched the customer_id in the orders table.

Output

When we run the example code above, we'll get a list of all customers and their orders, as follows:

+----+----------+------+------------+--------+---------------------+---------------------+---------------------+
| id | name     | age | email      | id     | order_date          | shipped_date        | customer_id         |
+----+----------+------+------------+--------+---------------------+---------------------+---------------------+
|  1 | John Doe |   35 | john@doe.com |    100 | 2021-01-01 00:00:00 | 2021-01-02 00:00:00 |                   1 |
|  1 | John Doe |   35 | john@doe.com |    101 | 2021-01-03 00:00:00 | 2021-01-03 00:00:00 |                   1 |
|  2 | Jane Doe |   30 | jane@doe.com |    102 | 2021-01-02 00:00:00 | 2021-01-04 00:00:00 |                   2 |
+----+----------+------+------------+--------+---------------------+---------------------+---------------------+

This output shows a list of all customers and their corresponding orders.

Explanation

In the example above, we used the FROM clause with two tables: customers and orders. We then used the SELECT statement to retrieve all columns from both tables. Finally, we joined these tables using the WHERE clause to match the id from the customers table with the customer_id in the orders table.

Use

The FROM clause is required for any SELECT statement that retrieves data from a specific table or tables. It allows you to specify the tables from which you want to select data, and can also be used to join multiple tables together.

Important Points

• You can list multiple tables in the FROM clause, separated by a comma.
• You can join multiple tables together using the WHERE clause, as shown in the example above.
• The FROM clause is required for any SELECT statement that retrieves data from a specific table or tables.

Summary

In this tutorial, we discussed how to use the FROM clause in MySQL. We covered the syntax, example, output, explanation, use, and important points of the FROM clause. With this knowledge, you can now use the FROM clause in your MySQL queries to select data from one or more tables.