SQL COUNT() Function
The COUNT()
function returns the number of rows that matches a specified criterion.
Example​
Find the total number of rows in the Products
table:
SELECT COUNT(\*)
FROM Products;
Syntax​
SELECT COUNT(_column_name_) FROM _table_name_ WHERE _condition_;
Demo Database​
Below is a selection from the Products table used in the examples:
ProductID | ProductName | SupplierID | CategoryID | Unit | Price |
---|---|---|---|---|---|
1 | Chais | 1 | 1 | 10 boxes x 20 bags | 18 |
2 | Chang | 1 | 1 | 24 - 12 oz bottles | 19 |
3 | Aniseed Syrup | 1 | 2 | 12 - 550 ml bottles | 10 |
4 | Chef Anton's Cajun Seasoning | 2 | 2 | 48 - 6 oz jars | 22 |
5 | Chef Anton's Gumbo Mix | 2 | 2 | 36 boxes | 21.35 |
Specify Column​
You can specify a column name instead of the asterix symbol (*)
.
If you specify a column name instead of (*)
, NULL values will not be counted.
Example​
Find the number of products where the ProductName
is not null:
SELECT COUNT(ProductName)
FROM Products;
Add a WHERE Clause​
You can add a WHERE
clause to specify conditions:
Example​
Find the number of products where Price
is higher than 20:
SELECT COUNT(ProductID)
FROM Products
WHERE Price > 20;
Ignore Duplicates​
You can ignore duplicates by using the DISTINCT
keyword in the COUNT()
function.
If DISTINCT
is specified, rows with the same value for the specified column will be counted as one.
Example​
How many different prices are there in the Products
table:
SELECT COUNT(DISTINCT Price)
FROM Products;
Use an Alias​
Give the counted column a name by using the AS
keyword.
Example​
Name the column "Number of records":
SELECT COUNT(\*) AS \[Number of records\]
FROM Products;
Use COUNT() with GROUP B​
Here we use the COUNT()
function and the GROUP BY
clause, to return the number of records for each category in the Products table:
Example​
SELECT COUNT(\*) AS \[Number of records\], CategoryID
FROM Products
GROUP BY CategoryID;