Fix #28 - Created rule G-1080 Avoid using the same expression on both sides of a relational comparison operator or a logical operator.

Author: kibeha

docs/4-language-usage/1-general/g-1080.md

@@ -0,0 +1,34 @@
+# G-1080: Avoid using the same expression on both sides of a relational comparison operator or a logical operator.
+
+!!! tip "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)
+
+``` sql
+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)
+
+``` sql
+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;
+```