Hi,

The GROUP BY statement in SQL is used to arrange identical data into groups. This statement is often used with aggregate functions (like COUNT, SUM, MAX, MIN, AVG) to group the result-set by one or more columns. Here’s what happens when you use GROUP BY:

Grouping Data: GROUP BY enables you to combine rows that have the same values in specified columns into summary rows, like gathering all the entries from different employees who work in the same department.

Multiple Columns: You can group by more than one column. For instance, if you group by both department and job title, the resulting summary rows represent unique combinations of department and job title.

GROUP BY gathers rows into groups and aggregates their other column values. HAVING then allows you to apply conditions to these groups.