????????????????

????SQL>Select * from dave a??bl b where a.id=b.id(+);    -- ??? ???+?? ??ù????where
??????????
???????+???????????+??????????????+ ???????????????м?????????????????????д??????????????????????????????
????SQL>Select * from dave a??bl b where a.id(+)=b.id;
????On??where??????
??????????????????????????????????????????????????м????????????????????????????????
?????????left jion???on??where?????????????￡?
????1?? on??????????????????????????????????on?е??????????棬???????????е?????
????2??where?????????????????ú???????????й???????????????????left join????壨?????????????????????????????????????
????????????????
??????1??tab2 id size
????1 10
????2 20
????3 30
??????2??tab2size name
????10 AAA
????20 BBB
????20 CCC
????????SQL:
????1??select* form tab1 left join tab2 on (tab1.size = tab2.size) where tab2.name=’AAA’
????2??select* form tab1 left join tab2 on (tab1.size = tab2.sizeandtab2.name=’AAA’)
?????????SQL??????
????1???м??
????on????:
????tab1.size = tab2.size  tab1.id tab1.size tab2.size tab2.name
????1 10 10 AAA
????2 20 20 BBB
????2 20 20 CCC
????3 30 (null) (null)
????| |
????2??????м?????
????where ??????
????tab2.name=’AAA’
????tab1.id tab1.size tab2.size tab2.name
????1 10 10 AAA
?????????SQL??????
????1???м??
????on????:
????tab1.size = tab2.size and tab2.name=’AAA’
????(??????????????????е???) tab1.id tab1.size tab2.size tab2.name
????1 10 10 AAA
????2 20 (null) (null)
????3 30 (null) (null)
??????????????????????left join??right join??full join?????????????on????????????涼????left??right???е?????full?????left??right??????????????inner jion?????????????????????on?к?where?У??????????????????
????????????????????????????????????????????on??where????