MySQL/MariaDB 常用函数收录

a_mysql_function_extension.md

目录

1. month_days.sql：获取当前日期月份的天
2. date_verify.sql：校验字符是否符合日期格式要求
3. json_maker.sql: 从sp连接的字符串生成JSON
4. clear_num.sql：将字符串转成数值,清理非字符
5. str_split.sql: 将字符串转json数组

date_verify.sql

/*
    test on MariaDB-10.5.10
*/
drop function if exists date_verify;

create function date_verify(date char(32), format char(30))
  returns tinyint
  not deterministic
  sql security definer
  comment '判定输入是否日期要求'
begin
/*判定输入是否日期要求（返回值：1-正确 0-错误）*/

declare v_date datetime;
-- declare v_format varchar(20) default '%Y-%m-%d %H:%i:%s'; -- 默认日期格式
declare v_min_date datetime default '1900-01-01 00:00:00'; -- 最小的日期
declare v_max_date datetime default '2099-12-31 23:59:59'; -- 最大的日期

select str_to_date(date,format) into v_date;

-- 不符合日期格式,无法转datetime
if v_date is null then
    return 0;
end if;

-- 小于最小值
if v_min_date is not null then
    if v_date < v_min_date then
        return 0;
    end if;
end if;

-- 大于最小值
if v_max_date is not null then
    if v_date > v_max_date then
        return 0;
    end if;
end if;

return 1;

end;

json_maker.sql

/*
    test on MariaDB-10.5.10
  
    eg:
        select json_maker('A^B^C', '1^2^3','^');
    result:
        {"A":"1","B":"2","C":"3"}
*/

DROP FUNCTION IF EXISTS json_maker;

CREATE FUNCTION `json_maker`(FIELDS TEXT, MY_VALUES TEXT, SP varchar(10)) RETURNS text CHARSET utf8
BEGIN
/* Generate JSON from string concatenated by `SP`

params：
    Make sure the keys and values are in the same order ~

    FIELDS: json's keys
    MY_VALUES: json's values
    SP: separator for `FIELDS` and `MY_VALUES`
*/
    DECLARE JSON_STR TEXT;
    DECLARE I INT DEFAULT 1;

    DECLARE KEY_NAME_TMP VARCHAR(100);
    DECLARE VAL_NAME_TMP VARCHAR(500);
    DECLARE KEY_VAL_TMP VARCHAR(1000);

    -- get fields number
    SELECT LENGTH(FIELDS)-LENGTH(REPLACE(FIELDS,SP,'' )) + 1 INTO @FIELDS_LEN;
    -- SELECT LENGTH(MY_VALUES)-LENGTH(REPLACE(MY_VALUES,SP,'' )) + 1 INTO @MY_VALUES_LEN;

    WHILE I <= @FIELDS_LEN DO

        SET KEY_NAME_TMP = SUBSTRING_INDEX(SUBSTRING_INDEX(FIELDS, SP,I),SP,-1);
        SET VAL_NAME_TMP = SUBSTRING_INDEX(SUBSTRING_INDEX(MY_VALUES, SP,I),SP,-1);
        SET KEY_VAL_TMP = CONCAT(JSON_QUOTE(KEY_NAME_TMP), ':', JSON_QUOTE(VAL_NAME_TMP));

        SET JSON_STR = CONCAT_WS(',', JSON_STR, KEY_VAL_TMP);

        SET I = I + 1;
    end while;
    SET JSON_STR = CONCAT('{', JSON_STR, '}');
    RETURN JSON_STR;
END;

month_days.sql

/*
    test on MariaDB-10.5.10
*/
drop function if exists month_days;

create function month_days(date datetime) returns tinyint comment '获取当前日期月份的天数'
begin
    return dayofmonth(last_day(date));
end;

mysql_function_extension.md

/* test on MariaDB-10.5.10

eg:
    select clear_num('dfsa1&23,98f%');
result:
    123.98

*/

drop function if exists clear_num;

CREATE FUNCTION clear_num(V_NUM varchar(100)) RETURNS DECIMAL(18,2) BEGIN /* get a clear number, conver string to number.

',' & ',' & '.' Is treated as a numeric decimal point. Modify it at line 22 if necessary

*/ DECLARE V_RESULT TEXT; DECLARE I INT DEFAULT 1;

-- get char number of V_NUM
SELECT char_length(V_NUM) INTO @V_LEN;

WHILE I <= @V_LEN DO

	SELECT right(left(V_NUM, I), 1) INTO @V_CHAR;
    
    IF @V_CHAR REGEXP('^[，,.]$') > 0 THEN
		SET V_RESULT = CONCAT_WS('', V_RESULT, '.');

	ELSEIF @V_CHAR REGEXP('^[0-9]$') > 0 THEN
		SET V_RESULT = CONCAT_WS('', V_RESULT, @V_CHAR);
	END IF;

    SET I = I + 1;

end while;

RETURN V_RESULT + 0;

END $$;

str_split.sql

/*
    test on MariaDB-10.5.10
*/

drop function if exists str_split;

create function str_split(v_str varchar(50), v_sp varchar(10)) returns json
begin
    /*
     String to JSON array by the separator
     eg.
        select str_split('www.baidu.com','.');
     return:
        '["www", "baidu", "com"]'
     */
    declare v_len int;
    declare i int default 1;
    declare v_json_array json default '[]';

    set v_len = length(v_str) - length(replace(v_str, v_sp, '')) + 1;

    while i <= v_len do
        set v_json_array = json_array_insert(v_json_array, concat('$[', i-1, ']'), substring_index(substring_index(v_str, v_sp, i), v_sp, -1));

        set i = i + 1;
    end while;

    return v_json_array;
end;