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??????????????????????????????????????????????????小?????????????????????????校??????????????
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????-------------------------------------------------
????a?? id name b?? id job parent_id
????1 ??3 1 23 1
????2 ???? 2 34 2
????3 ???? 3 34 4
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???????1?????????????????INNER JOIN???纬???屑??????????????????
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????WHERE C.ID=O.CUSTOMER_ID;
???????2????????????????????????????INNER JOIN???纬???屑????????????ON??????????????????
????SELECTO.ID??O.ORDER_NUMBER??C.ID??C.NAME
????FROM CUSTOMERS C INNER JOIN ORDERS O ON C.ID=O.CUSTOMER_ID;
???????????OUTER JOIN????
?????????????????????????????????????校???????????????????些?小?????????????????????LEFT OUTER JOIN?????????????RIGHT OUTER JOIN????????????FULL OUTER JOIN????
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????FROM ORDERS O LEFT OUTER JOIN CUSTOMERS C ON C.ID=O.CUSTOMER_ID;
???????4???????????RIGHT OUTER JOIN??
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????FROM ORDERS O RIGHT OUTER JOIN CUSTOMERS C ON C.ID=O.CUSTOMER_ID;
???????WHERE????????ON??????????????????????纾�
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????SELECTO.ID??O.ORDER_NUMBER??O.CUSTOMER_ID??C.ID??C.NAME
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????WHERE O.ORDER_NUMBER<>'MIKE_ORDER001';
???????6???????5?械?WHERE???????ON???妾�
????SELECTO.ID??O.ORDER_NUMBER??O.CUSTOMER_ID??C.ID??C.NAME
????FROM ORDERS O LEFT OUTER JOIN CUSTOMERS C ONC.ID=O.CUSTOMER_ID AND O.ORDER_NUMBER<>'MIKE_ORDER001';
?????????5?????6????????????????????????????6???????????????????????????写???????????ON??????????????????????屑?????????????写??WHERE????小?
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???????MySQL?????????????????????????写?????Oracle??DB2?????????????????????????????????????????????
???????8???????????????????????????????7????????
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????FROM ORDERS O LEFT OUTER JOIN CUSTOMERS C ON C.ID=O.CUSTOMER_ID
????UNION
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????FROM ORDERS O RIGHT OUTER JOIN CUSTOMERS C ON C.ID=O.CUSTOMER_ID;
????SQL????????????????????????
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???????????SQL????????????????????
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???????+???????????+?????????????? + ???????????????屑?????????????????????写??????????????????????????????
??????

???路???
??????????????????
2023/3/23 14:23:39???写?貌??????????
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