SQL GROUP BY

The SQL GROUP BY statement is used along with the aggregate functions to group the result dataset by one or more database table columns.

SQL GROUP BY Statement Syntax

SELECT ColumnName1, ColumnName2, ... , aggregate_function (ColumnName)
FROM TableName
WHERE predicates
GROUP BY ColumnName1, ColumnName2, ... 

The aggregate_function could be COUNT, SUM, MAX, MIN, AVG, …

SQL GROUP BY Statement Example

Table: DailyHours

Example 1
We want to find out the total hours for each department:

SELECT Department, SUM(Hours) AS TotalHours
FROM DailyHours
GROUP BY Department

The result will look like:

Example 2
Sometime we should use the GROUP BY statement on more than one column, for example, we want to find the total hours for each department each day:

SELECT Department, WorkingDate, SUM(Hours) AS TotalHours
FROM DailyHours
GROUP BY Department, WorkingDate

The result will look like: