• 时间格式化操作

SELECT TO_CHAR(SYSDATE, 'YYYY-MM-DD HH24:MI:SS') FROM DUAL;SELECT TO_DATE('2018-07-20 14:41:27', 'YYYY-MM-DD HH24:MI:SS') FROM DUAL;

• 根据生日（TimeStamp）查询年龄

SELECT TO_CHAR(SYSDATE, 'yyyy') - TO_CHAR(T.BIRTHDAY, 'yyyy') AGE FROM TABLE T;

• 取随机数

-- 取(0,1)之间的小数SELECT DBMS_RANDOM.VALUE FROM DUAL;-- 取0或1，四舍五入SELECT ROUND(DBMS_RANDOM.VALUE) FROM DUAL;

• 对小数的操作

-- 圆周率πSELECT ACOS(-1) FROM DUAL;  -- 3.14159265358979-- FLOOR：取整数位SELECT FLOOR(2345.67) FROM DUAL;    -- 2345-- CEIL：大于或等于的最小整数SELECT CEIL(3.1415927) FROM DUAL;   -- 4-- ROUND：四舍五入SELECT ROUND(3.1415926) FROM DUAL;  -- 3SELECT ROUND(3.1415926,4) FROM DUAL;    -- 3.1416-- TRUNC：截取指定精度SELECT TRUNC(3.1415926) FROM DUAL;  -- 3SELECT TRUNC(3.1415926,4) FROM DUAL;    -- 3.1415

参考资料