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'
 GROUP BY DeptID

Returns the data of the example pivot table which answers the question "How many Units did we sell in each Region for every Ship Date?":

   SELECT Region, Ship_Date, SUM(Units) AS Sum_of_Units
     FROM FlatData
 GROUP BY Region, Ship_Date

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)

See also

• Aggregate function

External links

• SQL Snippets: SQL Features Tutorials - Grouping Rows with GROUP BY
• MySQL GROUP BY and HAVING Clause with Examples