diff --git a/src/azure.py b/src/azure.py
index 2e55dc3..05e6f96 100644
--- a/src/azure.py
+++ b/src/azure.py
@@ -1,16 +1,18 @@
 
 # %% Import dependencies ----
 from dataclasses import dataclass
-from typing import Dict, Any, Iterable
-from pandas import DataFrame
+from typing import Dict, Any
+
 from sqlalchemy import create_engine, inspect
+
+import pandas as pd
 import urllib
 
 
-# %%
+# %% Models
 @dataclass(frozen=True)
 class ConnectionSettings:
-    """Connection Settings."""
+    """Connection Settings"""
     server: str
     database: str
     username: str
@@ -19,10 +21,10 @@ class ConnectionSettings:
     timeout: int = 30
 
 
+# %% Connection
 class AzureDbConnection:
-    """
-    Azure SQL database connection.
-    """
+    """Azure SQL database connection."""
+
     def __init__(self, conn_settings: ConnectionSettings, echo: bool = False) -> None:
         conn_params = urllib.parse.quote_plus(
             'Driver=%s;' % conn_settings.driver +
@@ -36,29 +38,29 @@ class AzureDbConnection:
         )
         conn_string = f'mssql+pyodbc:///?odbc_connect={conn_params}'
 
-        self.db = create_engine(conn_string, echo=echo)
+        self._db = create_engine(conn_string, echo=echo)
 
     def connect(self) -> None:
-        """Estimate connection."""
-        self.conn = self.db.connect()
+        """Estimate connection"""
+        self._conn = self._db.connect()
 
-    def get_tables(self) -> Iterable[str]:
-        """Get list of tables."""
-        inspector = inspect(self.db)
+    def get_tables(self) -> list[str]:
+        """Get list of tables"""
+        inspector = inspect(self._db)
         return [t for t in inspector.get_table_names()]
 
-    def insert(self, inserted_data: DataFrame, target_table: str, db_mapping: Dict[str, Any], chunksize: int = 10000) -> None:
+    def insert(self, inserted_data: pd.DataFrame, target_table: str, db_mapping: Dict[str, Any], chunksize: int = 10000) -> None:
         inserted_data.to_sql(
-            con=self.db,
+            con=self._db,
             schema='dbo',
             name=target_table,
-            if_exists='append',  # or replace
+            if_exists='replace',  # or append
             index=False,
             chunksize=chunksize,
             dtype=db_mapping
         )
 
     def dispose(self) -> None:
-        """Dispose opened connections."""
-        self.conn.close()
-        self.db.dispose()
+        """Dispose opened connections"""
+        self._conn.close()
+        self._db.dispose()