additional endpoint mechanism and overhead advance mapping by flat method

api/additional_methods.py

@@ -0,0 +1,19 @@
+from db import dbGetMany, dbGetOne, dbInsert, dbUpdate
+from loguru import logger
+import werkzeug
+
+
+def get_overhead_advance_flat_mapping_by_flat(user, token_info, flatId=None):
+    return dbGetOne(user, token_info, {
+            "statement": """
+SELECT 
+  id
+  ,overhead_advance
+  ,flat
+  FROM overhead_advance_flat_mapping_t
+  WHERE flat = %s
+                         """, 
+            "params": (flatId, )
+        }
+    )
+