Group by (SQL)

A GROUP BY statement in SQL specifies that a SQL SELECT statement partitions result rows into groups, based on their values in one or several columns. Typically, grouping is used to apply some sort of aggregate function for each group.[1][2]

The result of a query using a GROUP BY statement contains one row for each group. This implies constraints on the columns that can appear in the associated SELECT clause. As a general rule, the SELECT clause may only contain columns with a unique value per group. This includes columns that appear in the GROUP BY clause as well as aggregates resulting in one value per group.[3]

  1. ^ "SQL GROUP BY Statement". www.w3schools.com. Retrieved 2020-09-18.
  2. ^ shkale-msft. "GROUP BY (Transact-SQL) - SQL Server". docs.microsoft.com. Retrieved 2020-09-18.
  3. ^ "SQL Grouping and Aggregation". databaselecture.com. Retrieved 2020-12-09.