OR Vs UNION

From: <Saminathan_Seerangan_at_i2.com>
Date: Mon, 23 Jun 2003 21:55:17 -0700
Message-ID: <F001.005B834B.20030623213452@fatcity.com>

Hi All,

Could someone explain to me which one is best in the following two queries w.r.t performance?

Thanks
Sami

Query1)

---

select distinct empployee_id from employees where department_id=10 or department_id=20
/

Query2)

---

select employee_id from employees where department_id=10 union
select employee_id from employees where department_id=20
/

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Received on Mon Jun 23 2003 - 23:55:17 CDT