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sbt1
Yak Posting Veteran
89 Posts |
 Posted - 2003-12-12 : 06:42:55
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| I have an app which generates queries on the fly. Here's a typical one:SELECT TaskDates.DateValue,TaskDates.StartTime,TaskDates.EndTime,TaskDates.Resource,TaskDates.Status,TaskDates.Confirmed,TaskDates.Locked,TaskDates.CallFirstRequired,TaskDates.Duration,TaskDates.OTDuration,TaskDates.Customer,TaskDates.TaskID,TaskDates.Type,TaskDates.ID,Tasks.TaskDescription,Tasks.JobNumber FROM TaskDates INNER JOIN Tasks ON TaskDates.TaskID=Tasks.TaskID WHERE (TaskDates.Resource = 'Fred' and TaskDates.DateValue > 01/01/2004 and TaskDates.Type = 5)Some queries have more tests in the WHERE clause.Question: for optimum performance, should different type fields appear before others in the query? In other words, should an indexed integer field be placed before a non-indexed string type, etc.? |
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Merkin
Funky Drop Bear Fearing SQL Dude!
4970 Posts |
Posted - 2003-12-12 : 06:44:59
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| Select list order shouldn't matterHowever, if you are using ADO to call the database, you want to put any Text or Image fields last. If you don't ADO gets confused and you get some odd results.Damian |
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sbt1
Yak Posting Veteran
89 Posts |
Posted - 2003-12-12 : 07:00:15
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| Actually, I'm using OLE DB from a Visual C++ app.Should I follow the same rule with OLE DB? |
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Merkin
Funky Drop Bear Fearing SQL Dude!
4970 Posts |
Posted - 2003-12-12 : 07:01:37
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I'm not sure about that.But I'm sure it wouldn't hurt  Damian |
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Does the order of fields in a query effect speed?