MySql 函数

Posted 2021-12-01 scmath

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自定义函数 create function <name>（）

　　　　　　　returns [varchar(20)]

　　　　　 begin ....　　

　　　　　 end;

CREATE FUNCTION getGrade (mark INT) RETURNS VARCHAR (20)
BEGIN
    RETURN (
        CASE floor(mark / 10)
        WHEN 5 THEN
            ‘不及格‘
        WHEN 6 THEN
            ‘需要努力‘
        WHEN 8 THEN
            ‘成绩优秀‘
        ELSE
            ‘成绩良好‘
        END
    );

END ;

SELECT
    getGrade (70);

随机产生姓名：

　　【注意】

1. varchar与char 数组的区别，
  　　 char：定长，效率高，一般用于固定长度的表单提交数据存储；例如：身份证号，手机号，电话，密码等
  
  varchar：不定长，效率偏低
2. 截取字符串，不能用ln(2)，用substring()函数，
3. 取字符串长度时，char_length()返回实际长度76个汉字，用length()返回76*3=228个字符；

CREATE FUNCTION create_name()
RETURNS VARCHAR(20)
BEGIN
DECLARE ln  VARCHAR(300);
DECLARE fn1 VARCHAR(300);
DECLARE fn2 VARCHAR(300);

SET ln=‘赵钱孙李周吴郑王冯陈褚卫蒋沈韩杨朱秦尤许何吕施张孔曹严华金魏陶姜戚谢邹喻柏水窦章云苏潘葛奚范彭郎鲁韦昌马苗凤花方俞任袁柳鲍史唐费廉岑薛雷贺倪汤滕殷罗毕郝‘;
SET fn1=‘哲莹泰秦艳恭真原倩偌倚倜兼益凌准陵陶都挽莱莲莫茶莉莓荷莜莎唏唤峰峻徒徐阅涛涟消浴浩海流涧润涕浪涩家宽宴容宾姬娟娥绣朗朕保东文辉力明玲健世彩朗郎笑宗雨涵纪亭甜禹‘;
SET fn2=‘哲莹泰秦艳恭真原倩偌倚倜兼益凌准陵陶都挽莱莲莫茶莉莓荷莜莎唏唤峰峻徒徐阅涛涟消浴浩海流涧润涕浪涩家宽宴容宾姬娟娥绣朗朕保东文辉力明玲健世彩朗郎笑宗雨涵纪亭甜禹‘;

RETURN CONCAT(SUBSTRING(ln,CEIL(RAND()*CHAR_LENGTH(ln)),1),SUBSTRING(fn1,CEIL(RAND()*CHAR_LENGTH(fn1)),1),SUBSTRING(fn2,CEIL(RAND()*CHAR_LENGTH(fn2)),1));

END;
SELECT create_name();

汉字转拼音（全拼）：

　　【注意】

1. 先建表
2. 字典

#汉字转拼音过程
CREATE TABLE IF NOT EXISTS `t_base_pinyin` (
  `pin_yin_` varchar(255) CHARACTER SET gbk NOT NULL,
  `code_` int(11) NOT NULL,
  PRIMARY KEY (`code_`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
-- 插入数据--
INSERT INTO t_base_pinyin (pin_yin_,code_)  VALUES ("a", 20319),("ai", 20317),("an", 20304),("ang", 20295),("ao", 20292),("ba", 20283),("bai", 20265),("ban", 20257),("bang", 20242),("bao", 20230),("bei", 20051),("ben", 20036),("beng", 20032),("bi", 20026),("bian", 20002),("biao", 19990),("bie", 19986),("bin", 19982),("bing", 19976),("bo", 19805),("bu", 19784),("ca", 19775),("cai", 19774),("can", 19763),("cang", 19756),("cao", 19751),("ce", 19746),("ceng", 19741),("cha", 19739),("chai", 19728),("chan", 19725),("chang", 19715),("chao", 19540),("che", 19531),("chen", 19525),("cheng", 19515),("chi", 19500),("chong", 19484),("chou", 19479),("chu", 19467),("chuai", 19289),("chuan", 19288),("chuang", 19281),("chui", 19275),("chun", 19270),("chuo", 19263),("ci", 19261),("cong", 19249),("cou", 19243),("cu", 19242),("cuan", 19238),("cui", 19235),("cun", 19227),("cuo", 19224),("da", 19218),("dai", 19212),("dan", 19038),("dang", 19023),("dao", 19018),("de", 19006),("deng", 19003),("di", 18996),("dian", 18977),("diao", 18961),("die", 18952),("ding", 18783),("diu", 18774),("dong", 18773),("dou", 18763),("du", 18756),("duan", 18741),("dui", 18735),("dun", 18731),("duo", 18722),("e", 18710),("en", 18697),("er", 18696),("fa", 18526),("fan", 18518),("fang", 18501),("fei", 18490),("fen", 18478),("feng", 18463),("fo", 18448),("fou", 18447),("fu", 18446),("ga", 18239),("gai", 18237),("gan", 18231),("gang", 18220),("gao", 18211),("ge", 18201),("gei", 18184),("gen", 18183),("geng", 18181),("gong", 18012),("gou", 17997),("gu", 17988),("gua", 17970),("guai", 17964),("guan", 17961),("guang", 17950),("gui", 17947),("gun", 17931),("guo", 17928),("ha", 17922),("hai", 17759),("han", 17752),("hang", 17733),("hao", 17730),("he", 17721),("hei", 17703),("hen", 17701),("heng", 17697),("hong", 17692),("hou", 17683),("hu", 17676),("hua", 17496),("huai", 17487),("huan", 17482),("huang", 17468),("hui", 17454),("hun", 17433),("huo", 17427),("ji", 17417),("jia", 17202),("jian", 17185),("jiang", 16983),("jiao", 16970),("jie", 16942),("jin", 16915),("jing", 16733),("jiong", 16708),("jiu", 16706),("ju", 16689),("juan", 16664),("jue", 16657),("jun", 16647),("ka", 16474),("kai", 16470),("kan", 16465),("kang", 16459),("kao", 16452),("ke", 16448),("ken", 16433),("keng", 16429),("kong", 16427),("kou", 16423),("ku", 16419),("kua", 16412),("kuai", 16407),("kuan", 16403),("kuang", 16401),("kui", 16393),("kun", 16220),("kuo", 16216),("la", 16212),("lai", 16205),("lan", 16202),("lang", 16187),("lao", 16180),("le", 16171),("lei", 16169),("leng", 16158),("li", 16155),("lia", 15959),("lian", 15958),("liang", 15944),("liao", 15933),("lie", 15920),("lin", 15915),("ling", 15903),("liu", 15889),("long", 15878),("lou", 15707),("lu", 15701),("lv", 15681),("luan", 15667),("lue", 15661),("lun", 15659),("luo", 15652),("ma", 15640),("mai", 15631),("man", 15625),("mang", 15454),("mao", 15448),("me", 15436),("mei", 15435),("men", 15419),("meng", 15416),("mi", 15408),("mian", 15394),("miao", 15385),("mie", 15377),("min", 15375),("ming", 15369),("miu", 15363),("mo", 15362),("mou", 15183),("mu", 15180),("na", 15165),("nai", 15158),("nan", 15153),("nang", 15150),("nao", 15149),("ne", 15144),("nei", 15143),("nen", 15141),("neng", 15140),("ni", 15139),("nian", 15128),("niang", 15121),("niao", 15119),("nie", 15117),("nin", 15110),("ning", 15109),("niu", 14941),("nong", 14937),("nu", 14933),("nv", 14930),("nuan", 14929),("nue", 14928),("nuo", 14926),("o", 14922),("ou", 14921),("pa", 14914),("pai", 14908),("pan", 14902),("pang", 14894),("pao", 14889),("pei", 14882),("pen", 14873),("peng", 14871),("pi", 14857),("pian", 14678),("piao", 14674),("pie", 14670),("pin", 14668),("ping", 14663),("po", 14654),("pu", 14645),("qi", 14630),("qia", 14594),("qian", 14429),("qiang", 14407),("qiao", 14399),("qie", 14384),("qin", 14379),("qing", 14368),("qiong", 14355),("qiu", 14353),("qu", 14345),("quan", 14170),("que", 14159),("qun", 14151),("ran", 14149),("rang", 14145),("rao", 14140),("re", 14137),("ren", 14135),("reng", 14125),("ri", 14123),("rong", 14122),("rou", 14112),("ru", 14109),("ruan", 14099),("rui", 14097),("run", 14094),("ruo", 14092),("sa", 14090),("sai", 14087),("san", 14083),("sang", 13917),("sao", 13914),("se", 13910),("sen", 13907),("seng", 13906),("sha", 13905),("shai", 13896),("shan", 13894),("shang", 13878),("shao", 13870),("she", 13859),("shen", 13847),("sheng", 13831),("shi", 13658),("shou", 13611),("shu", 13601),("shua", 13406),("shuai", 13404),("shuan", 13400),("shuang", 13398),("shui", 13395),("shun", 13391),("shuo", 13387),("si", 13383),("song", 13367),("sou", 13359),("su", 13356),("suan", 13343),("sui", 13340),("sun", 13329),("suo", 13326),("ta", 13318),("tai", 13147),("tan", 13138),("tang", 13120),("tao", 13107),("te", 13096),("teng", 13095),("ti", 13091),("tian", 13076),("tiao", 13068),("tie", 13063),("ting", 13060),("tong", 12888),("tou", 12875),("tu", 12871),("tuan", 12860) ,("tui", 12858),("tun", 12852),("tuo", 12849),("wa", 12838),("wai", 12831),("wan", 12829),("wang", 12812),("wei", 12802),("wen", 12607),("weng", 12597),("wo", 12594),("wu", 12585),("xi", 12556),("xia", 12359),("xian", 12346),("xiang", 12320),("xiao", 12300),("xie", 12120),("xin", 12099),("xing", 12089),("xiong", 12074),("xiu", 12067),("xu", 12058),("xuan", 12039),("xue", 11867),("xun", 11861),("ya", 11847),("yan", 11831),("yang", 11798),("yao", 11781),("ye", 11604),("yi", 11589),("yin", 11536),("ying", 11358),("yo", 11340),("yong", 11339),("you", 11324),("yu", 11303),("yuan", 11097),("yue", 11077),("yun", 11067),("za", 11055),("zai", 11052),("zan", 11045),("zang", 11041),("zao", 11038),("ze", 11024),("zei", 11020),("zen", 11019),("zeng", 11018),("zha", 11014),("zhai", 10838),("zhan", 10832),("zhang", 10815),("zhao", 10800),("zhe", 10790),("zhen", 10780),("zheng", 10764),("zhi", 10587),("zhong", 10544),("zhou", 10533),("zhu", 10519),("zhua", 10331),("zhuai", 10329),("zhuan", 10328),("zhuang", 10322),("zhui", 10315),("zhun", 10309),("zhuo", 10307),("zi", 10296),("zong", 10281),("zou", 10274),("zu", 10270),("zuan", 10262),("zui", 10260),("zun", 10256),("zuo", 10254);
-- 建立汉字转换拼音函数
DROP FUNCTION IF EXISTS to_pinyin;
DELIMITER $
CREATE FUNCTION to_pinyin(NAME VARCHAR(255) CHARSET gbk)
RETURNS VARCHAR(255) CHARSET gbk
BEGIN
    DECLARE mycode INT;
    DECLARE tmp_lcode VARCHAR(2) CHARSET gbk;
    DECLARE lcode INT;
    DECLARE tmp_rcode VARCHAR(2) CHARSET gbk;
    DECLARE rcode INT;

    DECLARE mypy VARCHAR(255) CHARSET gbk DEFAULT ‘‘;
    DECLARE lp INT;

    SET mycode = 0;
    SET lp = 1;

    SET NAME = HEX(NAME);

    WHILE lp < LENGTH(NAME) DO

        SET tmp_lcode = SUBSTRING(NAME, lp, 2);
        SET lcode = CAST(ASCII(UNHEX(tmp_lcode)) AS UNSIGNED); 
        SET tmp_rcode = SUBSTRING(NAME, lp + 2, 2);
        SET rcode = CAST(ASCII(UNHEX(tmp_rcode)) AS UNSIGNED); 
        IF lcode > 128 THEN
            SET mycode =65536 - lcode * 256 - rcode ;
            SELECT CONCAT(mypy,pin_yin_) INTO mypy FROM t_base_pinyin WHERE CODE_ >= ABS(mycode) ORDER BY CODE_ ASC LIMIT 1;
            SET lp = lp + 4;
        ELSE
            SET mypy = CONCAT(mypy,CHAR(CAST(ASCII(UNHEX(SUBSTRING(NAME, lp, 2))) AS UNSIGNED)));
            SET lp = lp + 2;
        END IF;
    END WHILE;
    RETURN LOWER(mypy);
END;
$
DELIMITER ;
-- 使用方法
select to_pinyin(‘测试拼音‘);  #输出ceshipinyin

汉字转拼音（首字母）

fristPinyin ：此函数是将一个中文字符串的第一个汉字转成拼音字母（例如："中国人"->Z）

CREATE FUNCTION `fristPinyin`(P_NAME VARCHAR(255)) RETURNS varchar(255) CHARSET utf8
BEGIN
    DECLARE V_RETURN VARCHAR(255);
    SET V_RETURN = ELT(INTERVAL(CONV(HEX(left(CONVERT(P_NAME USING gbk),1)),16,10), 
        0xB0A1,0xB0C5,0xB2C1,0xB4EE,0xB6EA,0xB7A2,0xB8C1,0xB9FE,0xBBF7, 
        0xBFA6,0xC0AC,0xC2E8,0xC4C3,0xC5B6,0xC5BE,0xC6DA,0xC8BB,
        0xC8F6,0xCBFA,0xCDDA,0xCEF4,0xD1B9,0xD4D1),    
    ‘A‘,‘B‘,‘C‘,‘D‘,‘E‘,‘F‘,‘G‘,‘H‘,‘J‘,‘K‘,‘L‘,‘M‘,‘N‘,‘O‘,‘P‘,‘Q‘,‘R‘,‘S‘,‘T‘,‘W‘,‘X‘,‘Y‘,‘Z‘);
    RETURN V_RETURN;
END

pinyin ：此函数是将一个中文字符串对应拼音母的每个相连 (例如："中国人"->ZGR)

CREATE FUNCTION `pinyin`(P_NAME VARCHAR(255)) RETURNS varchar(255) CHARSET utf8
BEGIN
    DECLARE V_COMPARE VARCHAR(255);
    DECLARE V_RETURN VARCHAR(255);
    DECLARE I INT;
    SET I = 1;
    SET V_RETURN = ‘‘;
    while I < LENGTH(P_NAME) do
        SET V_COMPARE = SUBSTR(P_NAME, I, 1);
        IF (V_COMPARE != ‘‘) THEN
            #SET V_RETURN = CONCAT(V_RETURN, ‘,‘, V_COMPARE);
            SET V_RETURN = CONCAT(V_RETURN, fristPinyin(V_COMPARE));
            #SET V_RETURN = fristPinyin(V_COMPARE);
        END IF;
        SET I = I + 1;
    end while;
    IF (ISNULL(V_RETURN) or V_RETURN = ‘‘) THEN
        SET V_RETURN = P_NAME;
    END IF;
    RETURN V_RETURN;
END

数字转汉字：

存储过程：

　　带参数循环综合实例

　　【注意】

1. IFNULL(expr1,expr2)的使用。
2. convert(value,type)转换函数：type可为 CHAR, BINARY, SIGNED, DATE, TIME, DECIMAL。
3. LPAD，RPAD(str,len,padstr)字符串填充函数。

#创建存储过程，添加num个学生
CREATE PROCEDURE addStudents(in num INT)
BEGIN

    DECLARE sid INT; 
    DECLARE i INT;
    SET i=1;
    SELECT IFNULL(MAX(studentid),‘00000‘) INTO sid FROM TStudent;

    WHILE i<=num DO
        INSERT INTO TStudent VALUES(
        LPAD(CONVERT(sid+i,char(5)),5,‘0‘),
        create_name(),
        IF(CEIL(rand()*10)%2=0,‘男‘,‘女‘),
        RPAD(CONVERT(CEIL(RAND()*100000000000000000),CHAR(18)),18,‘0‘),
        CONCAT(‘198‘,CONVERT(CEIL(RAND()*10),char),‘-‘,
                        LPAD(CONVERT(CEIL(RAND()*12),char),2,‘0‘),‘-‘,
                        LPAD(CONVERT(CEIL(RAND()*28),char),2,‘0‘)),
        CONCAT(to_pinyin(sname),‘@hotmail.com‘),
        CASE CEIL(RAND()*3) WHEN 1 THEN "java" when 2 THEN ‘net‘ ELSE ‘H5‘ END,
        now()
        );

        SET i=i+1;
    END WHILE;
    SELECT * FROM TStudent WHERE studentID>sid;
END;
CALL addStudents(10);

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