Logical query processing - techie

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Monday, February 4, 2019

Logical query processing



The order in which a query is written is not the order in which it is evaluated by SQL Server.

           5:  SELECT           <select  list>

           1:  FROM              <table  source>

           2:  WHERE           <search  condition>

           3:  GROUP  BY    <group by list>

           4:  HAVING          <search condition>

           6:  ORDER BY     <order by list>


Applying the logical order of operations to writing SELECT statements


                USE        AdventureWork2012;

                SELECT   SalesPersonID, YEAR(OrderDate)  AS  OrderYear
                FROM      Sales.SalesOrderHeader
                WHERE   CustomerID = 29974
                GROUP    SalesPersonID, YEAR(OrderDate)
                HAVING   COUNT(*)  > 1
                ORDER BSalesPersonID,  OrderYear;

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