oracle group by

GROUP BY is a clause in Oracle SQL that is used to group rows based on specified columns. It is often used in conjunction with aggregate functions such as COUNT, SUM, AVG, etc.

The basic syntax of the GROUP BY clause is as follows:

SELECT column1, column2, ..., aggregate_function(column)
FROM table
WHERE conditions
GROUP BY column1, column2, ...

In this syntax, `column1`, `column2`, etc. represent the columns by which you want to group the data. The aggregate functions perform calculations on each group of rows.

For example, let's say we have a table named "orders" with columns like "customer_id", "order_date", and "amount". If we want to calculate the total amount spent by each customer, we can use the GROUP BY clause as follows:

SELECT customer_id, SUM(amount) AS total_amount
FROM orders
GROUP BY customer_id;

This query will group the rows by "customer_id" and calculate the sum of the "amount" column for each group. The result will include the customer_id and the total_amount for each customer.