Where

5.3. Where#

Sometimes we only want to select rows from our dataset which meet a particular criteria. For example, we might only want to look at customers with a postcodes greater than 8000, or were an item costs more than $2.00.

To select rows based on a particular criteria, we use the WHERE` clause. The WHERE` clause comes after the SELECT and FROM statements.

The structure of the WHERE clause is as follows:

WHERE condition;

In SQL we can compare values using the following operators:

  • < less than

  • > greater than

  • <= less than or equal to

  • >= greater than or equal to

  • = check values are equal

  • != check values are not equal

Note

Note that we use a single = sign for comparisons in SQL.

Here is an example.

SELECT *
FROM customers
WHERE lastname = 'Montazerolghaem';

Note

Note! You might want to click the square button on the right of the code toolbar to make the example full screen before you run it.

We can also construct WHERE statements using multiple conditions using the keywords AND and OR separating each criterion.

SELECT *
FROM customers
WHERE id < 10 AND postcode > 8000;