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Unwanted cartesian results (a chronic problem for me!)

Posted on 2008-06-20
Medium Priority
Last Modified: 2013-12-25
I keep getting unwanted cartesian results in my join, no matter how long I work at this.  (Access SQL seems to give me a harder time than SQL Server.)

I want all records from the patient table and only one matching record each from the insurance table.  (There are multiple matches in the table.)
EpiscopalPatient.VisitNumber, EpiscopalPatient.MedRecordNumber,
FROM EpiscopalPatient 
LEFT JOIN EpiscopalInsurance 
ON EpiscopalPatient.MedRecordNumber = EpiscopalInsurance.MedicalRecordNumber

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Question by:AmyFPA
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Expert Comment

ID: 21832165
Does it matter which match it pulls from your insurance table?
LVL 27

Expert Comment

ID: 21832202
<There are multiple matches in the table>
Are you saying that  there can be more than one row in EpiscopalInsurance for a single MedicalRecordNumber?
If not then the inclusion of Visit Number in the Select list will result in one row for every PatName/Visit combination in EpiscopalPatient
LVL 93

Accepted Solution

Patrick Matthews earned 500 total points
ID: 21832203
EpiscopalPatient.VisitNumber, EpiscopalPatient.MedRecordNumber,
Max(EpiscopalInsurance.GuarName) AS Guardian
FROM EpiscopalPatient
LEFT JOIN EpiscopalInsurance
ON EpiscopalPatient.MedRecordNumber = EpiscopalInsurance.MedicalRecordNumber
GROUP BY EpiscopalPatient.PatName,
EpiscopalPatient.VisitNumber, EpiscopalPatient.MedRecordNumber

Author Closing Comment

ID: 31469196
You're wonderful!

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