Example
Table ORDERS
+---------+------------+----------+-------+--------+
| orderid | customerid | customer | total | items |
+---------+------------+----------+-------+--------+
| 1 | 1 | Bob | 1300 | 10 |
| 2 | 3 | Fred | 500 | 2 |
| 3 | 5 | Tess | 2500 | 8 |
| 4 | 1 | Bob | 300 | 6 |
| 5 | 2 | Carly | 800 | 3 |
| 6 | 2 | Carly | 1000 | 12 |
| 7 | 3 | Fred | 100 | 1 |
| 8 | 5 | Tess | 11500 | 50 |
| 9 | 4 | Jenny | 200 | 2 |
| 10 | 1 | Bob | 500 | 15 |
+---------+------------+----------+-------+--------+
- COUNT
Return the number of rows that satisfy a specific criteria in WHERE clause.
E.g.: Number of orders for each customer.
SELECT customer, COUNT(*) as orders
FROM orders
GROUP BY customer
ORDER BY customer
Result:
+----------+--------+
| customer | orders |
+----------+--------+
| Bob | 3 |
| Carly | 2 |
| Fred | 2 |
| Jenny | 1 |
| Tess | 2 |
+----------+--------+
- SUM
Return the sum of the selected column.
E.g.: Sum of the total and items for each customer.
SELECT customer, SUM(total) as sum_total, SUM(items) as sum_items
FROM orders
GROUP BY customer
ORDER BY customer
Result:
+----------+-----------+-----------+
| customer | sum_total | sum_items |
+----------+-----------+-----------+
| Bob | 2100 | 31 |
| Carly | 1800 | 15 |
| Fred | 600 | 3 |
| Jenny | 200 | 2 |
| Tess | 14000 | 58 |
+----------+-----------+-----------+
- AVG
Return the average value of a column of numeric value.
E.g.: Average order value for each customers.
SELECT customer, AVG(total) as avg_total
FROM orders
GROUP BY customer
ORDER BY customer
Result:
+----------+-----------+
| customer | avg_total |
+----------+-----------+
| Bob | 700 |
| Carly | 900 |
| Fred | 300 |
| Jenny | 200 |
| Tess | 7000 |
+----------+-----------+
- MAX
Return the highest value of a certain column or expression.
E.g.: Highest order total for each customers.
SELECT customer, MAX(total) as max_total
FROM orders
GROUP BY customer
ORDER BY customer
Result:
+----------+-----------+
| customer | max_total |
+----------+-----------+
| Bob | 1300 |
| Carly | 1000 |
| Fred | 500 |
| Jenny | 200 |
| Tess | 11500 |
+----------+-----------+
- MIN
Return the lowest value of a certain column or expression.
E.g.: Lowest order total for each customers.
SELECT customer, MIN(total) as min_total
FROM orders
GROUP BY customer
ORDER BY customer
Result:
+----------+-----------+
| customer | min_total |
+----------+-----------+
| Bob | 300 |
| Carly | 800 |
| Fred | 100 |
| Jenny | 200 |
| Tess | 2500 |
+----------+-----------+
