oracle小数点前零丢失的问题

原文链接：http://www.2cto.com/database/201109/105934.html

 

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 

作者“努力向前”

 

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自己的解决sql如下：

select dbid,to_char(round(alarmvalue,2),'fm9999999990.00')

from alarm