Fix #35 - Created rule G-7125 Always use CREATE OR REPLACE instead of CREATE alone.

Author: kibeha

docs/4-language-usage/7-stored-objects/1-general/g-7120.md

@@ -1,4 +1,4 @@
-# G-7120	Always add the name of the program unit to its end keyword.
+# G-7120: Always add the name of the program unit to its end keyword.
 
 !!! tip "Minor"
     Maintainability

docs/4-language-usage/7-stored-objects/1-general/g-7125.md

@@ -0,0 +1,56 @@
+# G-7125: Always use CREATE OR REPLACE instead of CREATE alone.
+
+!!! tip "Minor"
+    Maintainability
+
+## Reason
+
+Using `create` alone makes your scripts give an error if the program unit already exists, which makes the script not repeatable. It is good practice to use `create or replace` to avoid such errors.
+
+## Example (bad)
+
+``` sql
+create package body employee_api is
+   function employee_by_id (in_employee_id in employees.employee_id%type)
+      return employees%rowtype is
+      r_employee employees%rowtype;
+   begin
+      select *
+        into r_employee
+        from employees
+       where employee_id = in_employee_id;
+      
+      return r_employee;
+   exception
+      when no_data_found then
+         null;
+      when too_many_rows then
+         raise;
+   end employee_by_id;
+end employee_api;
+/
+```
+
+## Example (good)
+
+``` sql
+create or replace package body employee_api is
+   function employee_by_id (in_employee_id in employees.employee_id%type)
+      return employees%rowtype is
+      r_employee employees%rowtype;
+   begin
+      select *
+        into r_employee
+        from employees
+       where employee_id = in_employee_id;
+      
+      return r_employee;
+   exception
+      when no_data_found then
+         null;
+      when too_many_rows then
+         raise;
+   end employee_by_id;
+end employee_api;
+/
+```