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”
经过测试,怀疑是number转为char时,舍去了小数点前面的0
[sql] view plaincopy
- SQL> select to_char(num,‘999999999.999999999‘) from ml_test;
- TO_CHAR(NUM,‘999999999.9999999
- ------------------------------
- .421240000
- .421246543
- 65432.421243240
- 4.621240000
- SQL> select to_char(num) from ml_test;
- TO_CHAR(NUM)
- ----------------------------------------
- .42124
- .4212465434
- 65432.42124324
- 4.62124
- SQL> select to_char(0.99) from dual;
- TO_CHAR(0.99)
- -------------
- .99
--4.怎么解决,解决方案如下
(1)
[sql] view plaincopy
- SQL> select to_nmber(to_char(0.99)) from dual;
- TO_NUMBER(TO_CHAR(0.99))
- ------------------------
- 0.99
- SQL> select to_char(num,‘fm999999990.999999999‘) from ml_test;
- TO_CHAR(NUM,‘FM999999990.99999
- ------------------------------
- 0.42124
- 0.421246543
- 65432.42124324
- 4.62124
(2)使用case when 或 decode函数,取第一位是否为".", 补0 ,就ok了
[sql] view plaincopy
- SQL> select to_char(num,‘999999999.999999999‘) from ml_test;
- TO_CHAR(NUM,‘999999999.9999999
- ------------------------------
- .421240000
- .421246543
- 65432.421243240
- 4.621240000
- SQL> select to_char(num) from ml_test;
- TO_CHAR(NUM)
- ----------------------------------------
- .42124
- .4212465434
- 65432.42124324
- 4.62124
- SQL> select to_char(0.99) from dual;
- TO_CHAR(0.99)
- -------------
- .99