019 UPDATE: In the 10 years since I wrote this answer, more solutions have been uncovered that may yield better results. Also, SQL Server releases since then (especially SQL 2012) have introduced new T-SQL features that can be used to calculate medians. SQL Server releases have also improved its query optimizer which may affect perf of … Read more
2019 UPDATE: In the 10 years since I wrote this answer, more solutions have been uncovered that may yield better results. Also, SQL Server releases since then (especially SQL 2012) have introduced new T-SQL features that can be used to calculate medians. SQL Server releases have also improved its query optimizer which may affect perf of … Read more
They’re used in different places. group by modifies the entire query, like: But partition by just works on a window function, like row_number: A group by normally reduces the number of rows returned by rolling them up and calculating averages or sums for each row. partition by does not affect the number of rows returned, … Read more
As per the documentation: FROM (Transact-SQL): The keyword OUTER is marked as optional (enclosed in square brackets). In this specific case, whether you specify OUTER or not makes no difference. Note that while the other elements of the join clause is also marked as optional, leaving them out will make a difference. For instance, the entire type-part of the JOIN clause is optional, in which case … Read more
As per the documentation: FROM (Transact-SQL): The keyword OUTER is marked as optional (enclosed in square brackets). In this specific case, whether you specify OUTER or not makes no difference. Note that while the other elements of the join clause is also marked as optional, leaving them out will make a difference. For instance, the … Read more