parameters: (db_session, class_type)
return_statement: return count
docstring: 获取某张表的行数
docstring_summary: 获取某张表的行数
docstring_tokens: 获取某张表的行数
function: def query_table_count(db_session, class_type):
      ''' 获取某张表的行数 '''
      count = db_session.query(func.count('*')).select_from(class_type).scalar()
      return count
function_tokens: def query_table_count ( db_session , class_type ) : count = db_session . query ( func . count ( '*' ) ) . select_from ( class_type ) . scalar ( ) return count