clean up Agent and Client for re-run data generation

Author: xsqian

src/calls_analysis/db_management.py

@@ -227,7 +227,7 @@ def create_tables():
     # Create an engine:
     engine = DBEngine()
     # Create the schema's tables if it already exits, drop it
-    Base.metadata.drop_all(engine.engine)
+    # Base.metadata.drop_all(engine.engine)
     # Create the schema's tables
     Base.metadata.create_all(engine.engine)