G-1080: Avoid using the same expression on both sides of a relational comparison operator or a logical operator.

Minor

Maintainability, Efficiency, Testability

Reason

Using the same value on either side of a binary operator is almost always a mistake. In the case of logical operators, it is either a copy/paste error and therefore a bug, or it is simply wasted code and should be simplified.

This rule ignores operators +, * and ||, and expressions: 1=1, 1<>1, 1!=1, 1~=1 and 1^=1.

Example (bad)

select emp.first_name
      ,emp.last_name
      ,emp.salary 
      ,emp.hire_date
  from employees emp
 where emp.salary > 3000 or emp.salary > 3000
 order by emp.last_name, emp.first_name;

Example (good)

select emp.first_name
      ,emp.last_name
      ,emp.salary 
      ,emp.hire_date
  from employees emp
 where emp.salary > 3000
 order by emp.last_name, emp.first_name;