sql怎么把一行数据中的几列相加?答:1、创建测试表,create table test_num(fee_id number, fee1 number, fee2 number, fee_3 number);2、插入测试数据,insert into test_num values(1001, 1200,1800,3000);insert into test_num values(1002, 2200,6800,4055);insert into test_num values(1003, 3200,7800,3790);insert into ...