Example of SQL query describing COUNT function and GROUP BY

Problem: Write a query on TRANSACTIONS DB2 table to list down the number of orders (ORDER_ID) assigned to a particular transaction (TRANSACTION_ID).

Solution

We can use the below query to find out the number of orders assigned to a particular transaction id on TRANSACTIONS DB2 table.

Example

SELECT TRANSACTION_ID, COUNT(ORDER_ID) FROM TRANSACTIONS
   GROUP BY TRANSACTION_ID

We will use GROUP BY function on the ORDER_ID to fetch the result order wise. The COUNT function will count the number of orders. For example, we have below DB2 ORDERS table.

The result of our DB2 query will return the below result.