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#1: Negated SELECT query

Posted on 2009-03-17 17:42:43 by BobTheBowler

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3 tables are related by one-many links.
Employees ---<- Assets ---<- Maintenance

Employees can be assigned =3D> 0 Assets
Assets can have =3D> 0 occurances of Maintenance.

Assets table contains EmployeeIDs and MaintenanceIDs,
but no Foreign Key contraints.


Queries ...
1) which Employees do not have any Assets =3F
2) which Assets have not had any Maintenance =3F
These have been written successfully with Sub-Queries,

I would like to know how they can be done with only JOINs =3F
(that also means without the EXCEPT statement)
Is that too much of a challenge =3F (MySQL 5.0.67)







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