MySQL WHERE

The MySQL WHERE clause is used to filter rows in a query based on a specified condition or set of conditions. The WHERE clause is often used in conjunction with the SELECT statement to retrieve data that meets certain criteria. It is also used in other SQL statements, such as UPDATE, DELETE, and INSERT INTO ... SELECT.

The basic syntax of the WHERE clause is as follows:

SELECT columns
FROM table
WHERE condition;

Here’s how it works:

• columns are the columns you want to retrieve from the table.
• table is the name of the table you want to query.
• condition is the expression that specifies the filtering criteria. Rows that meet the condition are included in the result set.

Here are some examples of how to use the WHERE clause in MySQL:

1. Retrieve all columns from the employees table for employees who work in the “Sales” department:

   SELECT *
   FROM employees
   WHERE department = 'Sales';

2. Retrieve the names and prices of products with a price greater than $100:

   SELECT product_name, price
   FROM products
   WHERE price > 100;

3. Update the discount column for products with a price greater than $500:

   UPDATE products
   SET discount = 0.10
   WHERE price > 500;

4. Delete all records from the orders table with an order_date earlier than a specific date:

   DELETE FROM orders
   WHERE order_date < '2023-01-01';

The WHERE clause allows you to filter and manipulate data based on specific conditions, making it a fundamental part of SQL queries and operations. It is used to extract, update, or delete data based on the criteria you specify, which helps you work with the data in a more precise and targeted way.