The GROUP by statement is used with the aggregate functions to group the result by one or more columns.

GROUP by Syntax

SELECT column_name, aggregate_function(column_name) FROM table_name WHERE column_name operator value GROUP by column_name;

We have a table "employee" as below:

    employee
    id  first_name            last_name       salary
    .......................................................
    1   John                     Simp         10000
    2   Chris                    Hely         25000
    3   John                     Roy          20000
    4   Jenny                    Mill         35000
    5   Jenny                    Simpson      35000

GROUP by Example

Now we want to find occurrence of first name value in column "first_name" then you just need to write the below command:

SELECT first_name, COUNT(fistr_name) as count
FROM employee 
GROUP by first_name;

Result:

    first_name            count
    .............................
    John                  2
    Chris                 1
    Jenny                 2

Hope this will help you :)