Is union better than or

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От Michaël Fiey
Тема Is union better than or
Дата
Msg-id 000801bffd72$9abc6440$6400a8c0@pc03
обсуждение исходный текст
Список pgsql-general
Hi,
I wonder what's the best between these 2 commands :
First command :
SELECT * FROM TABLE1 WHERE COL1 like 'A%' AND COL2 LIKE 'B%' AND (COL3 LIKE 'C%' OR COL4 LIKE 'D%')
 
Second command :
SELECT * FROM TABLE1 WHERE COL1 like 'A%' AND COL2 LIKE 'B%' AND COL3 LIKE 'C%'
UNION
SELECT * FROM TABLE1 WHERE COL1 like 'A%' AND COL2 LIKE 'B%' AND COL4 LIKE 'D%'
 
Any help would be appreciated.
Thanks.

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