ambiguous

If I assign the same name to 2 columns in 2 different tables:

+--------------------------------------+
|              DEPARTMENT              |
+----------+----------------+----------+
| LOCATION |  DESCRIPTION   |  DEPT_NO |
+----------+----------------+----------+
| Bedrock  | Administration |     1    |
+----------+----------------+----------+

+--------------------------------+
|            EMPLOYEE            |
+---------+------------+---------+
| EMPL_ID | NAME_LAST  | DEPT_NO |
+---------+------------+---------+
|    1    | Slate      |     1   |
+---------+------------+---------+

select * from DEPARTMENT, Employee where dept_no = '1';

PG throws up:
ERROR:  Column 'dept_no' is ambiguous

Is this not allowed? or is my sql understanding wrong?


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