SQL 基础 SQL 首页 SQL 简介 SQL 语法 SQL select SQL distinct SQL where SQL AND & OR SQL Order By SQL insert SQL update SQL delete SQL 高级 SQL Top SQL Like SQL 通配符 SQL In SQL Between SQL Aliases SQL Join SQL Inner Join SQL Left Join SQL Right Join SQL Full Joi
通过查询获得某个字段的合计值，如果这个值位null将给出一个预设的默认值 select nvl(ob.bookingvalue，0) bookingvalue from blis_order o, blis_orderbooking ob where o.orderid=ob.orderid and o.orderid =125034 and ob.bookingtypeid = 215 and ob.status = 'Active'这里关心nvl的用法，nvl（arg,value）代表如果
