ORA-00918: column ambiguously defined

Hi,

I got ” ORA-00918: column ambiguously defined ” error in Oracle SQL .

Details of error are as follows.

ORA-00918: column ambiguously defined

The ORA-00918 error is related with the same column name in the join tables. When you use 2 column with the same name exists in the both tables when join two or more tables, you can get this error.

A column name used in a join exists in more than one table and is thus referenced ambiguously. In a join, any column name that occurs in more than one of the tables must be prefixed by its table name when referenced. The column should be referenced as TABLE.COLUMN or TABLE_ALIAS.COLUMN.

To solve this error, you need to use the Table alias or TABLE_NAME.COLUMN_NAME usage especially in the Table Join as follows.

SQL> SELECT employee_id, first_name,last_name,city, department_name
       FROM   hr.employees e 
       JOIN   hr.departments d
       ON     d.department_id = e.department_id 
       JOIN   hr.locations l
       ON     d.location_id = l.location_id where l.location_id>2400;

EMPLOYEE_ID FIRST_NAME           LAST_NAME                 CITY                           DEPARTMENT_NAME
----------- -------------------- ------------------------- ------------------------------ ------------------------------
        145 John                 Russell                   Oxford                         Sales
        146 Karen                Partners                  Oxford                         Sales
        147 Alberto              Errazuriz                 Oxford                         Sales
        148 Gerald

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