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Разница между JOIN и EXISTS в SELECT



 
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Hanna_89
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Joined: 01 Nov 2011
Posts: 29

PostPosted: Wed Feb 08, 2012 12:43 pm    Post subject: Разница между JOIN и EXISTS в SELECT Reply with quote

Здравствуйте!
Помогите, пожалуйста, разобраться: впервые столкнулась с EXISTS в SELECT. Чем отличается SELECT, если скажем, прописать так:
1)SELECT * INTO TABLE name_tab
FROM scarr
WHERE EXISTS ( select *
FROM spfli
WHERE carrid = scarr~carrid ).
2) SELECT * INTO TABLE name_tab
FROM scarr
INNER JOIN spfli scarr~carrid = spfli~carrid.

Когда нужно использовать EXISTS, а когда JOIN?
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Удав
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Age: 48
Joined: 25 Jan 2008
Posts: 580
Location: Москва

PostPosted: Thu Feb 09, 2012 2:08 pm    Post subject: Reply with quote

Hanna_89, почитайте справку к оператору SELECT.
Там же в оглавлении есть следующий пункт Selecting Lines.

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