BayaiM__ oracle函数_01
BayaiM__ oracle函数_01
Oracle函数
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行函数:
--ABS求绝对值
SELECT ABS(-1) FROM DUAL;
--SQRT求平方根
SELECT SQRT(361) FROM DUAL;
--POWER求m的n次幂
SELECT POWER(2,10), FROM DUAL;
--COS求弧度的余弦值
SELECT COS(3.1415) FROM DUAL;
--ARCCOS求弧度
SELECT ACOS(1) FROM DUAL;
--SIN求弧度的正弦值
SELECT SIN(3.1415) FROM DUAL;
--ARCSIN求弧度
SELECT ASIN(1) FROM DUAL;
--MOD求余数
SELECT MOD(100,90) FROM DUAL;
--CEIL进一圆整
SELECT CEIL(100.5) FROM DUAL;
--FLOOR去尾圆整
SELECT FLOOR(10.1) FROM DUAL;
--ROUND四舍五入取整
SELECT ROUND(10.1234,3) FROM DUAL;
--EXP求e的n次方
SELECT EXP(2) FROM DUAL;
--LN求e的对数
SELECT LN(20) FROM DUAL;
--LOG求对数
SELECT LOG(2,4) FROM DUAL;
--取当前日期
SELECT SYSDATE FROM DUAL;
--将ROWID转换为CHAR
SELECT ROWIDTOCHAR(ROWID) FROM SCOTT.EMP;
--将CHAR转换为ROWID
SELECT * FROM SCOTT.EMP WHERE ROWID=CHARTOROWID('AAAMfPAAEAAAAAgAAN');
--TRUNC截断取整
SELECT TRUNC(10.123456,5) FROM DUAL;
--求字符对应的ASCII码
SELECT ASCII('C') FROM DUAL;
--求ASCII码对应的字符
SELECT CHR(50) ROM DUAL;
--转换成小写
SELECT LOWER('ABCD') FROM DUAL;
--转换成大写
SELECT UPPER('abcd') FROM DUAL;
--将每个单词首字母大写
SELECT INITCAP('abcd efg') FROM DUAL;
--截取子串
SELECT SUBSTR('ABCDEFG',2,4) FROM DUAL; --从左向右
SELECT SUBSTR('ABCDEFG',-1,3) FROM DUAL; --从右向左
--求字符串长度
SELECT LENGTH('12345') FROM DUAL;
--求出现位置,给定母串,子串,起始位置,次数
SELECT INSTR('ABCDEFGE','E',4,1) FROM DUAL;
--向左补齐
SELECT LPAD('A',10,'B') FROM DUAL;
--向右补齐
SELECT RPAD('A',10,'B') FROM DUAL;
--去空格
SELECT TRIM(' ABC ') FROM DUAL;
SELECT LTRIM(' ABC ') FROM DUAL;
SELECT RTRIM(' ABC ') FROM DUAL;
--TO_DATE转换为日期
SELECT TO_DATE('2012-01-02','yyyy-MM-dd') FROM DUAL;
--求两个日期间的月份
SELECT MONTHS_BETWEEN(TO_DATE('2012-01-01','yyyy-MM-dd'),TO_DATE('2012-02-01','yyyy-MM-dd')) FROM DUAL;
--给日期加上一个自然月
SELECT ADD_MONTH(TO_DATE('2012-01-01','yyyy-MM-dd'),2) FROM DUAL;
--求下一天
SELECT NEXT_DAY(TO_DATE('2012-01-01','yyyy-MM-dd')) FROM DUAL;
--求指定日期所在月的最后一天
SELECT LAST_DAY(TO_DATE('2012-01-01','yyyy-MM-dd')) FROM DUAL;
--对日期四舍五入
SELECT ROUND(TO_DATE('2012-01-01','yyyy-MM-dd'),'YEAR') FROM DUAL;
SELECT ROUND(TO_DATE('2012-01-01','yyyy-MM-dd'),'MONTH') FROM DUAL;
SELECT ROUND(TO_DATE('2012-01-01','yyyy-MM-dd'),'DAY') FROM DUAL;
--对日期截断
SELECT TRUNC(TO_DATE('2012-01-01','yyyy-MM-dd'),'YEAR') FROM DUAL;
SELECT TRUNC(TO_DATE('2012-01-01','yyyy-MM-dd'),'MONTH') FROM DUAL;
SELECT TRUNC(TO_DATE('2012-01-01','yyyy-MM-dd'),'DAY') FROM DUAL;
--NVL空值转换,如果不是空就直接返回,如果是空就返回指定值
SELECT NVL(NULL,'A') FROM DUAL;
--DECODE条件输出转换
SELECT DECODE(1,1,'A',2,'B') FROM DUAL;
--TO_CHAR转换为字符串
SELECT TO_CHAR(SYSDATE,'yyyy-MM-dd hi24:mi:ss) FROM DUAL;
--TO_NUMBER字符转换为数字
SELECT TO_NUMBER('123') FROM DUAL;
--UID当前用户ID
SELECT USERNAME, USER_ID FROM DBA_USERS WHERE USER_ID = UID;
--分支
SELECT (CASE WHEN DUMMY='X' THEN 0 ELSE 1 END) FROM DUAL;
聚集函数:
--MAX 最大值
--MIN 最小值
--AVG 平均值
--STDDEV 标准差
--VARIANCE 协方差
--COUNT 计数
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
行函数:
--ABS求绝对值
SELECT ABS(-1) FROM DUAL;
--SQRT求平方根
SELECT SQRT(361) FROM DUAL;
--POWER求m的n次幂
SELECT POWER(2,10), FROM DUAL;
--COS求弧度的余弦值
SELECT COS(3.1415) FROM DUAL;
--ARCCOS求弧度
SELECT ACOS(1) FROM DUAL;
--SIN求弧度的正弦值
SELECT SIN(3.1415) FROM DUAL;
--ARCSIN求弧度
SELECT ASIN(1) FROM DUAL;
--MOD求余数
SELECT MOD(100,90) FROM DUAL;
--CEIL进一圆整
SELECT CEIL(100.5) FROM DUAL;
--FLOOR去尾圆整
SELECT FLOOR(10.1) FROM DUAL;
--ROUND四舍五入取整
SELECT ROUND(10.1234,3) FROM DUAL;
--EXP求e的n次方
SELECT EXP(2) FROM DUAL;
--LN求e的对数
SELECT LN(20) FROM DUAL;
--LOG求对数
SELECT LOG(2,4) FROM DUAL;
--取当前日期
SELECT SYSDATE FROM DUAL;
--将ROWID转换为CHAR
SELECT ROWIDTOCHAR(ROWID) FROM SCOTT.EMP;
--将CHAR转换为ROWID
SELECT * FROM SCOTT.EMP WHERE ROWID=CHARTOROWID('AAAMfPAAEAAAAAgAAN');
--TRUNC截断取整
SELECT TRUNC(10.123456,5) FROM DUAL;
--求字符对应的ASCII码
SELECT ASCII('C') FROM DUAL;
--求ASCII码对应的字符
SELECT CHR(50) ROM DUAL;
--转换成小写
SELECT LOWER('ABCD') FROM DUAL;
--转换成大写
SELECT UPPER('abcd') FROM DUAL;
--将每个单词首字母大写
SELECT INITCAP('abcd efg') FROM DUAL;
--截取子串
SELECT SUBSTR('ABCDEFG',2,4) FROM DUAL; --从左向右
SELECT SUBSTR('ABCDEFG',-1,3) FROM DUAL; --从右向左
--求字符串长度
SELECT LENGTH('12345') FROM DUAL;
--求出现位置,给定母串,子串,起始位置,次数
SELECT INSTR('ABCDEFGE','E',4,1) FROM DUAL;
--向左补齐
SELECT LPAD('A',10,'B') FROM DUAL;
--向右补齐
SELECT RPAD('A',10,'B') FROM DUAL;
--去空格
SELECT TRIM(' ABC ') FROM DUAL;
SELECT LTRIM(' ABC ') FROM DUAL;
SELECT RTRIM(' ABC ') FROM DUAL;
--TO_DATE转换为日期
SELECT TO_DATE('2012-01-02','yyyy-MM-dd') FROM DUAL;
--求两个日期间的月份
SELECT MONTHS_BETWEEN(TO_DATE('2012-01-01','yyyy-MM-dd'),TO_DATE('2012-02-01','yyyy-MM-dd')) FROM DUAL;
--给日期加上一个自然月
SELECT ADD_MONTH(TO_DATE('2012-01-01','yyyy-MM-dd'),2) FROM DUAL;
--求下一天
SELECT NEXT_DAY(TO_DATE('2012-01-01','yyyy-MM-dd')) FROM DUAL;
--求指定日期所在月的最后一天
SELECT LAST_DAY(TO_DATE('2012-01-01','yyyy-MM-dd')) FROM DUAL;
--对日期四舍五入
SELECT ROUND(TO_DATE('2012-01-01','yyyy-MM-dd'),'YEAR') FROM DUAL;
SELECT ROUND(TO_DATE('2012-01-01','yyyy-MM-dd'),'MONTH') FROM DUAL;
SELECT ROUND(TO_DATE('2012-01-01','yyyy-MM-dd'),'DAY') FROM DUAL;
--对日期截断
SELECT TRUNC(TO_DATE('2012-01-01','yyyy-MM-dd'),'YEAR') FROM DUAL;
SELECT TRUNC(TO_DATE('2012-01-01','yyyy-MM-dd'),'MONTH') FROM DUAL;
SELECT TRUNC(TO_DATE('2012-01-01','yyyy-MM-dd'),'DAY') FROM DUAL;
--NVL空值转换,如果不是空就直接返回,如果是空就返回指定值
SELECT NVL(NULL,'A') FROM DUAL;
--DECODE条件输出转换
SELECT DECODE(1,1,'A',2,'B') FROM DUAL;
--TO_CHAR转换为字符串
SELECT TO_CHAR(SYSDATE,'yyyy-MM-dd hi24:mi:ss) FROM DUAL;
--TO_NUMBER字符转换为数字
SELECT TO_NUMBER('123') FROM DUAL;
--UID当前用户ID
SELECT USERNAME, USER_ID FROM DBA_USERS WHERE USER_ID = UID;
--分支
SELECT (CASE WHEN DUMMY='X' THEN 0 ELSE 1 END) FROM DUAL;
聚集函数:
--MAX 最大值
--MIN 最小值
--AVG 平均值
--STDDEV 标准差
--VARIANCE 协方差
--COUNT 计数
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