Dec 22, 2012 · SQL does allow you to filter on the results of a GROUP BY -- it's called the HAVING clause. If you want to filter on something that could be determined prior to the grouping (i.e. everyone with FirstName = 'Mark'), that's done via WHERE.

May 30, 2017 · The GROUP BY clause instructs the DBMS to group the data and then perform the aggregate (function) on each group rather than on the entire result set. Aside from the aggregate calculation statements, every column in your SELECT statement must be present in the GROUP BY clause.

Jul 19, 2016 · This has always bothered me - why does the GROUP BY clause in a SQL statement require that I include all non-aggregate columns? These columns should be included by default - a kind of "GROUP BY *" - since I can't even run the query unless they're all included.

Sep 12, 2015 · That means *"group by the 1st column in your select clause". Always use GROUP BY 1 together with ORDER BY 1. You can also use GROUP BY 1,2,3... It is convenient, but you need to pay attention to that condition; the result may not be what you want if someone has modified your select columns and it's not visualized.

Jan 26, 2015 · Does "group by" clause automatically guarantee that the results will be ordered by that key? In other words, is it enough to write: select * from table group by a, b, c or does one have to write

Mar 10, 2010 · When using GROUP BY x statement, it fetches rows for each distinct value of column x. When using GROUP BY x, y statement, it fetches rows for each unique pair of values of column x and y. By adding more columns in the GROUP BY clause, more detail and more specific subsets of the data is created in query results; therefore, gaining higher granularity.

Feb 20, 2012 · Using this example, I want to return: RESTAURANT_NO ------------- 1 4 Since RESTAURANT_NO 2 and 3 both have locations in city C. I do not know how to group RESTAURANT_NO together while also trying only to select the groups that meet this requirement. EDIT: I got this working. However, there is one last thing that I still have not been …

Dec 22, 2012 · I do, however, have some sympathy for the question. Many people learning SQL think of "grouping" as something done in the context of sorting the rows. Something like "sort the cities in the US and group them by state in the output". Makes sense. But "group by" in SQL really means "summarize by" not "keep together".

Jun 17, 2010 · There's a legacy, non-standard feature of Microsoft SQL Server called ROLLUP. ROLLUP is an extension to the GROUP BY syntax and when it is used the order of the GROUP BY columns determines which columns should be grouped in …

Dec 3, 2015 · What can be done to get results faster? Update With proposed added index, I get results faster, but now I would like to get faster results with two inner joins as described above. Or eventually I could do additional 2 queries from tables MessageDirection and MessageType if nothing can be done to increase performance of below query.