1.問題起源
oracle 數據庫字段值為小於1的小數時，使用char類型處理，會丟失小數點前面的0
例如0.35就變成了.35
2.解決辦法:用to_char函數格式化數字顯示
select to_char(0.338,'fm9999999990.00') from dual;
結果:0.34
這裡重點要看 fm9999999999.99,表示整數部分最多10位,小數部分2位,fm表示去 掉轉位字符串後前面的空格,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
