The SQL COUNT(), AVG() and SUM() Functions
The COUNT() function returns the number of rows that matches a specified criterion.
The AVG() function returns the average value of a numeric column.
The SUM() function returns the total sum of a numeric column.
COUNT() Syntax
SELECT COUNT(column_name)
FROM table_name
WHERE condition;
AVG() Syntax
SELECT AVG(column_name)
FROM table_name
WHERE condition;
SUM() Syntax
SELECT SUM(column_name)
FROM table_name
WHERE condition;
COUNT() Example
SELECT COUNT(itemid)
FROM item;
Note: NULL values are not counted.
AVG() Example
The following SQL statement finds the average price of all products:
SELECT AVG(Price)
FROM items;
SUM() Example
SELECT SUM(ItemQty)
FROM items;