Fix for oracle schema parsing stated on the issue #7928 (#13545)

- **Description:** In this pull request, we address an issue related to
assigning a schema to the SQLDatabase class when utilizing an Oracle
database. The current implementation encounters a bug where, upon
attempting to execute a query, the alter session parse is not
appropriately defined for Oracle, leading to an error,
  - **Issue:** #7928,
  - **Dependencies:** No dependencies,
  - **Tag maintainer:** @baskaryan,

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/langchain/langchain/utilities/sql_database.py

@@ -402,6 +402,10 @@ class SQLDatabase:
                     # but `duckdb_engine` seemed to struggle with all of them:
                     # https://github.com/Mause/duckdb_engine/issues/796
                     connection.exec_driver_sql(f"SET search_path TO {self._schema}")
+                elif self.dialect == "oracle":
+                    connection.exec_driver_sql(
+                        f"ALTER SESSION SET CURRENT_SCHEMA = {self._schema}"
+                    )
                 else:  # postgresql and other compatible dialects
                     connection.exec_driver_sql("SET search_path TO %s", (self._schema,))
             cursor = connection.execute(text(command))