Fix sqlalchemy warnings when running tests (#733)

This has been bugging me when running my own tests that call langchain
methods :P

langchain/cache.py

@@ -4,8 +4,7 @@ from typing import Any, Dict, List, Optional, Tuple
 
 from sqlalchemy import Column, Integer, String, create_engine, select
 from sqlalchemy.engine.base import Engine
-from sqlalchemy.ext.declarative import declarative_base
-from sqlalchemy.orm import Session
+from sqlalchemy.orm import Session, declarative_base
 
 from langchain.schema import Generation
 

langchain/sql_database.py

@@ -86,7 +86,7 @@ class SQLDatabase:
         If the statement returns rows, a string of the results is returned.
         If the statement returns no rows, an empty string is returned.
         """
-        with self._engine.connect() as connection:
+        with self._engine.begin() as connection:
             if self._schema is not None:
                 connection.exec_driver_sql(f"SET search_path TO {self._schema}")
             cursor = connection.exec_driver_sql(command)

tests/unit_tests/llms/test_base.py

@@ -1,6 +1,6 @@
 """Test base LLM functionality."""
 from sqlalchemy import Column, Integer, Sequence, String, create_engine
-from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import declarative_base
 
 import langchain
 from langchain.cache import InMemoryCache, SQLAlchemyCache

tests/unit_tests/test_sql_database.py

@@ -40,7 +40,7 @@ def test_sql_database_run() -> None:
     engine = create_engine("sqlite:///:memory:")
     metadata_obj.create_all(engine)
     stmt = insert(user).values(user_id=13, user_name="Harrison")
-    with engine.connect() as conn:
+    with engine.begin() as conn:
         conn.execute(stmt)
     db = SQLDatabase(engine)
     command = "select user_name from user where user_id = 13"
@@ -54,7 +54,7 @@ def test_sql_database_run_update() -> None:
     engine = create_engine("sqlite:///:memory:")
     metadata_obj.create_all(engine)
     stmt = insert(user).values(user_id=13, user_name="Harrison")
-    with engine.connect() as conn:
+    with engine.begin() as conn:
         conn.execute(stmt)
     db = SQLDatabase(engine)
     command = "update user set user_name='Updated' where user_id = 13"

tests/unit_tests/test_sql_database_schema.py

@@ -57,7 +57,7 @@ def test_sql_database_run() -> None:
     engine = create_engine("duckdb:///:memory:")
     metadata_obj.create_all(engine)
     stmt = insert(user).values(user_id=13, user_name="Harrison")
-    with engine.connect() as conn:
+    with engine.begin() as conn:
         conn.execute(stmt)
     db = SQLDatabase(engine, schema="schema_a")
     command = 'select user_name from "user" where user_id = 13'