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SQL for beginners

Counting rows with COUNT #

So far we've only pulled raw rows out of a table. Sometimes you don't want the rows themselves, you want a summary of them, for example, "how many rows are there?" That's what aggregate functions are for: they take many rows and collapse them into a single value. COUNT is the simplest one, it counts rows.

SELECT
    COUNT(*)
FROM
    table_name;

COUNT(*) counts every row in the table, regardless of whether any column is NULL. As with any column, you can give the result a friendlier name with AS:

SELECT
    COUNT(*) AS total
FROM
    table_name;

Example #

SELECT
    COUNT(*) AS total
FROM
    customers;

Result:

+-------+
| total |
+-------+
|  10   |
+-------+

This tells us there are 10 rows in the customers table, without us having to fetch and count them ourselves.

Exercise #

Write a command that counts the total number of rows in the products table.

  • The result has a total column.
  • The value of total matches the number of rows in products.
Solution 
SELECT
    COUNT(*) AS total
FROM
    products;
Output will be displayed here