code: public int count(Entity where) throws SQLException {
  		Connection conn = null;
  		try {
  			conn = this.getConnection();
  			return runner.count(conn, where);
  		} catch (SQLException e) {
  			throw e;
  		} finally {
  			this.closeConnection(conn);
  		}
  	}
docs: 结果的条目数
  
  @param where 查询条件
  @return 复合条件的结果数
  @throws SQLException SQL执行异常