Fixing issue with MSSQL connection (#8040)

My team recently faced an issue while using MSSQL and passing a schema
name.

We noticed that "SET search_path TO {self.schema}" is being called for
us, which is not a valid ms-sql query, and is specific to postgresql
dialect.

We were able to run it locally after this fix.


---------

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

libs/langchain/langchain/utilities/sql_database.py

@@ -383,7 +383,9 @@ class SQLDatabase:
                     )
                 elif self.dialect == "bigquery":
                     connection.exec_driver_sql(f"SET @@dataset_id='{self._schema}'")
-                else:
+                elif self.dialect == "mssql":
+                    pass
+                else:  # postgresql and compatible dialects
                     connection.exec_driver_sql(f"SET search_path TO {self._schema}")
             cursor = connection.execute(text(command))
             if cursor.returns_rows: