1.問題起源 oracle 數(shù)據(jù)庫字段值為小于1的小數(shù)時(shí)，使用char類型處理，會丟失小數(shù)點(diǎn)前面的0 例如0.35就變成了.35 2.解決辦法:用to_char函數(shù)格式化數(shù)字顯示 select to_char(0.338,'fm9999999990.00') from dual; 結(jié)果:0.34 這里重點(diǎn)要看 fm9999999999.99,表示

　　1.問題起源

　　oracle 數(shù)據(jù)庫字段值為小于1的小數(shù)時(shí)，使用char類型處理，會丟失小數(shù)點(diǎn)前面的0

　　例如0.35就變成了.35

　　2.解決辦法:用to_char函數(shù)格式化數(shù)字顯示

　　select to_char(0.338,'fm9999999990.00') from dual;

　　結(jié)果:0.34

　　這里重點(diǎn)要看 fm9999999999.99,表示整數(shù)部分最多10位,小數(shù)部分2位,fm表示去 掉轉(zhuǎn)位字符串后前面的空格,不加fm,0.34前面會有空格的.

　　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