Oracle SQL join 注意事項意事項

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測試資料來源請先參考 Oracle DB 目錄

 


column ambiguously defined
欄位模棱兩可問題

例：

SELECT 

      employee_id,

      department_name,

      department_id

FROM

employees INNER JOIN departments

ON ( employees.department_id = departments.department_id);


錯誤：
ORA-00918: column ambiguously defined
00918. 00000 -  "column ambiguously defined"


其問題：
在 department_id
因為不知道要顯示employees還是departments的department_id

解法：指定來源表格

SELECT 

      employee_id,

      department_name,

      employees.department_id

FROM

employees INNER JOIN departments

ON ( employees.department_id = departments.department_id);


測試：





 

 







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