SQL GROUP BY

Sure! The GROUP BY clause in SQL is used to arrange identical data into groups. This is often used with aggregate functions like COUNT(), SUM(), AVG(), MIN(), and MAX() to perform calculations on each group of data.

Basic Syntax

SELECT column1, aggregate_function(column2)
FROM table_name
GROUP BY column1;

Example

Let's consider a simple table called Sales:

1. Count Sales by Salesperson

To find out how many sales each salesperson has made, you can use:

SELECT Salesperson, COUNT(*) AS NumberOfSales
FROM Sales
GROUP BY Salesperson;

Output:

2. Sum of Sales Amount by Salesperson

To get the total sales amount for each salesperson:

SELECT Salesperson, SUM(Amount) AS TotalSales
FROM Sales
GROUP BY Salesperson;

Output:

3. Average Sales Amount by Salesperson

To find the average sales amount for each salesperson:

SELECT Salesperson, AVG(Amount) AS AverageSales
FROM Sales
GROUP BY Salesperson;

Output:

Notes

• When using GROUP BY, every column in the SELECT statement that isn't an aggregate function must be included in the GROUP BY clause.
• You can also use HAVING to filter groups based on aggregate functions, which is similar to the WHERE clause but for groups.

Would you like more details or examples?