drop table test1;
create table test1
(column1 varchar2(30));
insert into test1 values(1234);
insert into test1 values(2345);
select * from test1 where column1 = 1234; –能够查询出来,不报错
insert into test1 values(‘aaaa’);
select * from test1 where column1 = 1234; –报错 ORA-01722:invalid number
–报错原因:隐私转换,首先尝试COLUMN1所有的记录都转换成NUMBER类型,但是当遇到字符串的时候,转换出错,无法进行,报错了。如果这些记录全部都是数字,那么就可以查询