The AVG() function returns the average value of a numeric column. Count data by using a totals query. You count data by using a totals query instead of a Total row when you need to count some or all of the records returned by a query. For example, you can count the number of sales transactions, or the number of transactions in a single city.

Convenzioni della sintassi Transact-SQL Transact-SQL Syntax Conventions. Questa funzione permette di ottenere il conteggio dei dati selezionati dalla query , fornendo direttamente come risultato il totale finale. If you specify DISTINCT, then you can specify only the query _partition_clause of the analytic_clause. The order_by_clause and windowing_clause are not allowed. Non importa quali valori sono archiviati nei record.
All these expressions work with MS SQL Server, Oracle and mySQL. NULL value will not be counted. In this article Syntax List. GROUP BY returns one records for each group.

Returns the number of items in the list list. NET Framework implementation of Enumerable. Note that there is optimization.
I am trying to create the query so it will tell me how many actors have three or more roles in the database. A combination of same values (on a column) will be treated as an individual group. The execution plan is more complex, but much less work – the query cost here is 0.

