add G-3183, closes #202

Author: PhilippSalvisberg

docs/4-language-usage/3-dml-and-sql/1-general/g-3183.md

@@ -0,0 +1,34 @@
+# G-3183: Always specify column aliases instead of expressions in GROUP BY clauses.
+
+!!! tip "Minor"
+    Readability, Maintainability
+
+## Restriction
+
+Oracle Database 23c
+
+## Reason
+
+Starting with Oracle Database 23c, it is possible to use a column alias in the `group by` clause instead of repeating the expression used in the `select` list.
+
+Unless you use `rollup`, `cube` or `grouping sets`, it is not necessary to use expressions in the `group by` clause.
+
+## Example (bad)
+
+``` sql
+select lower(job_id) as job
+      ,sum(salary) as sum_salary
+  from employees
+ group by lower(job_id)
+ order by job;
+```
+
+## Example (good)
+
+``` sql
+select lower(job_id) as job
+      ,sum(salary) as sum_salary
+  from employees
+ group by job
+ order by job;
+```