--INSTR函式
SELECT INSTR(' HELLO WORLD','H') FROM DUAL;
--LTRIM RTRIM函式
SELECT LTRIM('*HELLO=','*') FROM DUAL;
SELECT RTRIM('=HELLO=','=') FROM DUAL;
SELECT RTRIM(LTRIM('*HELLO*','*'),'*') FROM DUAL;
--TRIM函式
SELECT TRIM('*'FROM'*HELLO*') FROM DUAL;
--REPLACE函式
SELECT REPLACE('ABCDE','E','123') FROM DUAL;
 
--SUBSTR函式
SELECT SUBSTR('ABCDE',2,2) FROM DUAL;
--CEIL FLOOR函式
SELECT CEIL(6.01) FROM DUAL;
SELECT FLOOR(6.999) FROM DUAL;
--ROUND函式
SELECT ROUND(3.456,1) FROM DUAL;
--TRUNC函式            
SELECT TRUNC(3.456,1) FROM DUAL;
--RXTRACT函式
SELECT 
SYSDATE "DATE",
EXTRACT(YEAR FROM SYSDATE) "YEAR",
EXTRACT(
 
MONTH FROM SYSDATE) "MONTH",
EXTRACT(DAY FROM SYSDATE) "DAY",
EXTRACT(HOUR FROM SYSTIMESTAMP) "HOUR",--HOUR匹配的結果沒有加上時區，在中國執行的結果要小8個小時
EXTRACT(MINUTE FROM SYSTIMESTAMP) "MINUTE",
EXTRACT(SECOND FROM SYSTIMESTAMP) "SECOND"
FROM DUAL;
--TO_CHAR函式
SELECT
TO_CHAR(SYSDATE,'YYYY"年"MM"月"DD"日" HH24:MI:SS') "DATE" 
 
FROM DUAL