--INSTR函数

SELECT INSTR(' HELLO WORLD','H') FROM DUAL;

--LTRIM RTRIM函数

SELECT LTRIM('*HELLO=','*') FROM DUAL;

SELECT RTRIM('=HELLO=','=') FROM DUAL;

SELECT RTRIM(LTRIM('*HELLO*','*'),'*') FROM DUAL;

--TRIM函数

SELECT TRIM('*'FROM'*HELLO*') FROM DUAL;

--REPLACE函数

SELECT REPLACE('ABCDE','E','') FROM DUAL;

--SUBSTR函数

SELECT SUBSTR('ABCDE',2,2) FROM DUAL;

--CEIL FLOOR函数

SELECT CEIL(6.01) FROM DUAL;

SELECT FLOOR(6.999) FROM DUAL;

--ROUND函数

SELECT ROUND(3.456,1) FROM DUAL;

--TRUNC函数

SELECT TRUNC(3.456,1) FROM DUAL;

--RXTRACT函数

SELECT

SYSDATE "DATE",

EXTRACT(YEAR FROM SYSDATE) "YEAR",

EXTRACT(MONTH FROM SYSDATE) "MONTH",

EXTRACT(DAY FROM SYSDATE) "DAY",

EXTRACT(HOUR FROM SYSTIMESTAMP) "HOUR",--HOUR匹配的结果没有加上时区，在中国运行的结果要小8个小时

EXTRACT(MINUTE FROM SYSTIMESTAMP) "MINUTE",

EXTRACT(SECOND FROM SYSTIMESTAMP) "SECOND"

FROM DUAL;

--TO_CHAR函数

SELECT

TO_CHAR(SYSDATE,'YYYY"年"MM"月"DD"日" HH24:MI:SS') "DATE"

FROM DUAL