Re: rewriting query without using UNION

I don't see why would query with multiple unions necessarily degrade performance, but here is another way for writing your query:

select e.id, e.name, d.deptname from emp e, dept d where e.deptno=d.deptno and ( e.name='JOSE' or d.deptno=50) /

That would be a union of all employees from the department with deptno=50 plus the ones called "JOSE".

On 10/29/2003 12:54:26 PM, Linda Wang wrote:
> Hi,
> I wonder if there's a better way of writing the query below. Basically, I
> would like to return employee records where employee name='JOSE' + all
> employees in deptno=50. My query can have multiple 'OR' criterias where the
> next criteria maybe returning all employees with salary>60000 in addition to
> the above two criterias. Building the query with multiple UNIONs will
> definitely degrade the query performance. Is there a better way of rewriting
> the query?
>
> Thanks!
>
> linda
>
> select e.id, e.name, d.deptname from emp e, dept d
> where e.deptno=d.deptno and e.name='JOSE'
> union
> select e.id, e.name, d.deptname from emp e, dept d
> where e.deptno=d.deptno and d.deptno=50;
>
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Mladen Gogala
Oracle DBA

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Author: Mladen Gogala
  INET: mladen_at_wangtrading.com

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