oracle 优化or 更换in、exists、union几个字眼。测试没有问题！

根据实际情况选择相应的语句是。假设指数,or全表扫描，in 和not in 应慎用。否则会导致全表扫描。

 select *

   from T_Pro_Product

  where bar_code = 'nnnmmm'

     or name = 'nnnmmm'

     or no = 'nnnmmm';

select *

   from T_Pro_Product

  where 'nnnmmm' in (bar_code, name, no)

 --忧化

   select *

           from T_Pro_Product t1

          where exists

          (select 1

                   from T_Pro_Product tt1

                  where t1.bar_code = 'nnnmmm'

                 union all

                 select 1

                   from T_Pro_Product tt2

                  where t1.no = 'nnnmmm'

                 union all

                 select 1 from T_Pro_Product tt3 where t1.name like 'n%')

         --忧化

           select *

                   from T_Pro_Product t1

                  where t1.id in (select id

                                    from T_Pro_Product tt1

                                   where t1.bar_code = 'nnnmmm'

                                  union all

                                  select id

                                    from T_Pro_Product tt2

                                   where t1.no = 'nnnmmm'

                                  union all

                                  select id

                                    from T_Pro_Product tt3

                                   where t1.name = 'nnnmmm')