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SQL for beginners

Filtering a list with IN #

Checking a column against several possible values with OR gets repetitive fast. The IN keyword lets you list all the values you want to match in one place.

Syntax #

SELECT
    column_name
FROM
    table_name
WHERE
    column_name IN (value_1, value_2, value_3);

A row matches if column_name equals any of the values in the list.

Example #

SELECT
    *
FROM
    products
WHERE
    category IN ('Electronics', 'Fitness');

is equivalent to:

SELECT
    *
FROM
    products
WHERE
    category = 'Electronics'
    OR category = 'Fitness';

Result:

+----+-------------------+-------------+-------+
| id |       name        |  category   | price |
+----+-------------------+-------------+-------+
| 1  |  Wireless Mouse    | Electronics | 19.99 |
| 2  | Bluetooth Speaker  | Electronics | 45.5  |
| 3  |     Yoga Mat       |   Fitness   | 25.0  |
| 4  |   Running Shoes    |   Fitness   | 60.0  |
+----+-------------------+-------------+-------+

Products from the Home and Office categories are excluded, since neither category appears in the list.

Exercise #

Write a query that retrieves all columns from the products table, keeping only the rows where category is 'Electronics' or 'Fitness'.

  • The result has a category column.
  • The result contains exactly the rows where category is 'Electronics' or 'Fitness', and no others.
Solution 
SELECT
    *
FROM
    products
WHERE
    category IN ('Electronics', 'Fitness');
Output will be displayed here