Group by (SQL)

A GROUP BY statement in SQL specifies that a SQL SELECT statement returns a list that is grouped by one or more columns, usually in order to apply some sort of aggregate function to certain columns.

Examples:

Returns a list of Department IDs along with the sum of their sales for the date of January 1, 2000.

SELECT DeptID, SUM(SaleAmount) FROM Sales
WHERE SaleDate = '01-Jan-2000'

a group by statement can use a having clause to filter the number of rows.....

GROUP BY DeptID

Common grouping (aggregation) functions include:

• count(expression) - Quantity of matching records (per group)

• Sum(expression) - Summation of given value (per group)

• Min(expression) - Minimum of given value (per group)

• Max(expression) - Maximum of given value (per group)

• Avg(expression) - Average of given value (per group)