FULL OUTER JOINS should be used with caution


    The rule "FULL OUTER JOINS should be used with caution" in PL/SQL code means that when using a FULL OUTER JOIN, one should be aware of potential performance issues and other complications. FULL OUTER JOINS are used to combine the results of two or more tables, but they can be computationally expensive and can produce unexpected results if not used correctly. Therefore, it is important to understand the implications of using a FULL OUTER JOIN and to use it only when necessary.

Key Benefits

  • Performance: FULL OUTER JOINS can be slow and resource intensive; should be used with caution.
  • Accuracy: FULL OUTER JOINS can return incomplete or inaccurate results; should be used with caution.
  • Data Integrity: FULL OUTER JOINS can cause data integrity issues; should be used with caution.


Non-compliant Code Example

SELECT emp.first_name,
FROM employees emp 
FULL OUTER JOIN departments dept ON (emp.department_id = dept.department_id); --Non compliant code 
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