G-3190: Avoid using NATURAL JOIN.
Major
Changeability, Reliability
Reason
A natural join joins tables on equally named columns. This may comfortably fit on first sight, but adding logging columns to a table (changed_by, changed_date) will result in inappropriate join conditions.
Example (bad)
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24 | select department_name
,last_name
,first_name
from employees natural join departments
order by department_name
,last_name;
DEPARTMENT_NAME LAST_NAME FIRST_NAME
------------------------------ ------------------------- --------------------
Accounting Gietz William
Executive De Haan Lex
...
alter table departments add modified_at date default on null sysdate;
alter table employees add modified_at date default on null sysdate;
select department_name
,last_name
,first_name
from employees natural join departments
order by department_name
,last_name;
No data found
|
Example (good)
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13 | select d.department_name
,e.last_name
,e.first_name
from employees e
join departments d on (e.department_id = d.department_id)
order by d.department_name
,e.last_name;
DEPARTMENT_NAME LAST_NAME FIRST_NAME
------------------------------ ------------------------- --------------------
Accounting Gietz William
Executive De Haan Lex
...
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