Subject | Re: [firebird-support] VIEW optimization |
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Author | Ann Harrison |
Post date | 2016-04-07T20:08:06Z |
On Thu, Apr 7, 2016 at 3:41 PM, Ann Harrison <aharrison@...> wrote:On Thu, Apr 7, 2016 at 2:27 PM, Gabor Boros gaborboros@... [firebird-support] <firebird-support@yahoogroups.com> wrote:2016. 04. 07. 19:31 keltezéssel, 'Mark Rotteveel' mark@...
[firebird-support] írta:Just in case you think Firebird should be able to ignore parts of an outer join,let me disillusion you.select d.DepartmentName from Departments dleft outer join Employees e on e.DeptID = d.DeptIDSuppose you have 10 Departments and 10 Employees, but all theEmployees have the same DeptID. Then you should get the sameDepartmentName ten times.The left outer join will return the nine unmatched Departments, returningone DepartmentName for each unmatched Department. The name of theDepartment with 10 Employees will be returned 10 time.Good luck,Ann