1.问题起源 oracle 数据库字段值为小于1的小数时，使用char类型处理，会丢失小数点前面的0 例如0.35就变成了.35 2.解决办法:用to_char函数格式化数字显示 select to_char(0.338,'fm9999999990.00') from dual; 结果:0.34 这里重点要看 fm9999999999.99,表示
1.问题起源
oracle 数据库字段值为小于1的小数时，使用char类型处理，会丢失小数点前面的0
例如0.35就变成了.35
2.解决办法:用to_char函数格式化数字显示
select to_char(0.338,'fm9999999990.00') from dual;
结果:0.34
这里重点要看 fm9999999999.99,表示整数部分最多10位,小数部分2位,fm表示去 掉转位字符串后前面的空格,不加fm,0.34前面会有空格的.
3.with的使用
with tmp1 as (
select 1 as a, 2 as b from dual
union
select 1 as a, 3 as b from dual
union
select 1 as a, 4 as b from dual
),
tmp2 as (
select 1 as a, 2 as b from dual
union
select 1 as a, 3 as b from dual
union
select 2 as a, 4 as b from dual
)
select tmp1.*,tmp2.*
from tmp1 join tmp2
on tmp1.a = tmp2.a
，