53

我想从一个表中选择一个 blob col，base64 对其进行编码并将其插入到另一个表中。有什么方法可以做到这一点，而无需将数据从数据库和我的应用程序中往返？

4

8 回答 8

62

我一直在寻找同样的东西，我刚刚看到 MySQL 5.6 有几个新的字符串函数支持这个功能：TO_BASE64和FROM_BASE64。

于 2011-09-08T16:27:07.473 回答
18

当编码字符串为 32 字节（空格）时，来自http://wi-fizzle.com/downloads/base64.sql的函数包含一些错误，例如 BASE64_ENCODE(CONCAT(CHAR(15), CHAR(32)))。这是修正功能

DELIMITER $$

USE `YOUR DATABASE`$$

DROP TABLE IF EXISTS core_base64_data$$
CREATE TABLE core_base64_data (c CHAR(1) BINARY, val TINYINT)$$
INSERT INTO core_base64_data VALUES 
('A',0), ('B',1), ('C',2), ('D',3), ('E',4), ('F',5), ('G',6), ('H',7), ('I',8), ('J',9),
('K',10), ('L',11), ('M',12), ('N',13), ('O',14), ('P',15), ('Q',16), ('R',17), ('S',18), ('T',19),
('U',20), ('V',21), ('W',22), ('X',23), ('Y',24), ('Z',25), ('a',26), ('b',27), ('c',28), ('d',29),
('e',30), ('f',31), ('g',32), ('h',33), ('i',34), ('j',35), ('k',36), ('l',37), ('m',38), ('n',39),
('o',40), ('p',41), ('q',42), ('r',43), ('s',44), ('t',45), ('u',46), ('v',47), ('w',48), ('x',49),
('y',50), ('z',51), ('0',52), ('1',53), ('2',54), ('3',55), ('4',56), ('5',57), ('6',58), ('7',59),
('8',60), ('9',61), ('+',62), ('/',63), ('=',0) $$

DROP FUNCTION IF EXISTS `BASE64_ENCODE`$$

CREATE DEFINER=`YOUR DATABASE`@`%` FUNCTION `BASE64_ENCODE`(input BLOB) RETURNS BLOB
    DETERMINISTIC
    SQL SECURITY INVOKER
BEGIN
    DECLARE ret BLOB DEFAULT '';
    DECLARE done TINYINT DEFAULT 0;
    IF input IS NULL THEN
        RETURN NULL;
    END IF;
each_block:
    WHILE NOT done DO BEGIN
        DECLARE accum_value BIGINT UNSIGNED DEFAULT 0;
        DECLARE in_count TINYINT DEFAULT 0;
        DECLARE out_count TINYINT;
each_input_char:
        WHILE in_count < 3 DO BEGIN
            DECLARE first_char BLOB(1);

            IF LENGTH(input) = 0 THEN
                SET done = 1;
                SET accum_value = accum_value << (8 * (3 - in_count));
                LEAVE each_input_char;
            END IF;

            SET first_char = SUBSTRING(input,1,1);
            SET input = SUBSTRING(input,2);

            SET accum_value = (accum_value << 8) + ASCII(first_char);
            SET in_count = in_count + 1;
        END; END WHILE;

        -- We've now accumulated 24 bits; deaccumulate into base64 characters
        -- We have to work from the left, so use the third byte position and shift left
        CASE
            WHEN in_count = 3 THEN SET out_count = 4;
            WHEN in_count = 2 THEN SET out_count = 3;
            WHEN in_count = 1 THEN SET out_count = 2;
            ELSE RETURN ret;
        END CASE;

        WHILE out_count > 0 DO BEGIN
            BEGIN
                DECLARE out_char CHAR(1);
                DECLARE base64_getval CURSOR FOR SELECT c FROM core_base64_data WHERE val = (accum_value >> 18);
                OPEN base64_getval;
                FETCH base64_getval INTO out_char;
                CLOSE base64_getval;
                SET ret = CONCAT(ret,out_char);
                SET out_count = out_count - 1;
                SET accum_value = accum_value << 6 & 0xffffff;
            END;
        END; END WHILE;
        CASE
            WHEN in_count = 2 THEN SET ret = CONCAT(ret,'=');
            WHEN in_count = 1 THEN SET ret = CONCAT(ret,'==');
            ELSE BEGIN END;
        END CASE;

    END; END WHILE;
    RETURN ret;
END$$

DELIMITER ;
于 2012-08-27T08:33:06.160 回答
13 
SELECT `id`,`name`, TO_BASE64(content) FROM `db`.`upload`

这会将 blob 值从内容列转换为 base64 字符串。然后你可以用这个字符串做任何你想做的事情，甚至将它插入另一个表

于 2016-06-15T14:17:09.903 回答
5

看起来没有，虽然它是请求的，并且有一个 UDF。

编辑：或者有……这个。啊。

于 2008-12-11T05:23:41.267 回答
5

对于那些感兴趣的人，这些是迄今为止唯一的选择：

1）使用这些功能：

http://wi-fizzle.com/downloads/base64.sql

2）如果你已经有sys_eval UDF，（Linux）你可以这样做：

sys_eval(CONCAT("echo '",myField,"' | base64"));

已知第一种方法很慢。第二个问题是编码实际上发生在 MySQL 的“外部”，这可能存在编码问题（除了您使用 sys_* 函数添加的安全风险之外）。

不幸的是，在 MySQL 中没有 UDF 编译版本（应该更快）也没有原生支持（Posgresql 支持它！）。

MySQL 开发团队似乎对实现它不感兴趣，因为这个功能已经存在于其他语言中，这对我来说似乎很愚蠢。

于 2011-08-17T06:12:45.373 回答
2

另一个不需要支持表的自定义实现：

drop function if exists base64_encode;
create function base64_encode(_data blob)
returns text
begin
    declare _alphabet char(64) default 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    declare _lim int unsigned default length(_data);
    declare _i int unsigned default 0;
    declare _chk3 char(6) default '';
    declare _chk3int int default 0;
    declare _enc text default '';

    while _i < _lim do
        set _chk3 = rpad(hex(binary substr(_data, _i + 1, 3)), 6, '0');
        set _chk3int = conv(_chk3, 16, 10);
        set _enc = concat(
            _enc
            ,                  substr(_alphabet, ((_chk3int >> 18) & 63) + 1, 1)
            , if (_lim-_i > 0, substr(_alphabet, ((_chk3int >> 12) & 63) + 1, 1), '=')
            , if (_lim-_i > 1, substr(_alphabet, ((_chk3int >>  6) & 63) + 1, 1), '=')
            , if (_lim-_i > 2, substr(_alphabet, ((_chk3int >>  0) & 63) + 1, 1), '=')
        );
        set _i = _i + 3;
    end while;

    return _enc;
end;

drop function if exists base64_decode;
create function base64_decode(_enc text)
returns blob
begin
    declare _alphabet char(64) default 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
    declare _lim int unsigned default 0;
    declare _i int unsigned default 0;
    declare _chr1byte tinyint default 0;
    declare _chk4int int default 0;
    declare _chk4int_bits tinyint default 0;
    declare _dec blob default '';
    declare _rem tinyint default 0;
    set _enc = trim(_enc);
    set _rem = if(right(_enc, 3) = '===', 3, if(right(_enc, 2) = '==', 2, if(right(_enc, 1) = '=', 1, 0)));
    set _lim = length(_enc) - _rem;

    while _i < _lim
    do
        set _chr1byte = locate(substr(_enc, _i + 1, 1), binary _alphabet) - 1;
        if (_chr1byte > -1)
        then
            set _chk4int = (_chk4int << 6) | _chr1byte;
            set _chk4int_bits = _chk4int_bits + 6;

            if (_chk4int_bits = 24 or _i = _lim-1)
            then
                if (_i = _lim-1 and _chk4int_bits != 24)
                then
                    set _chk4int = _chk4int << 0;
                end if;

                set _dec = concat(
                    _dec
                    ,                        char((_chk4int >> (_chk4int_bits -  8)) & 0xff)
                    , if(_chk4int_bits >  8, char((_chk4int >> (_chk4int_bits - 16)) & 0xff), '\0')
                    , if(_chk4int_bits > 16, char((_chk4int >> (_chk4int_bits - 24)) & 0xff), '\0')
                );
                set _chk4int = 0;
                set _chk4int_bits = 0;
            end if;
        end if;
        set _i = _i + 1;
    end while;

    return substr(_dec, 1, length(_dec) - _rem);
end;

要旨

您应该在解码后转换字符集：convert(base64_decode(base64_encode('ёлка')) using utf8)

于 2018-03-07T12:29:18.790 回答
1

如果您在 < 5.6 时需要这个，我偶然发现了这个似乎工作正常的 UDF：

https://github.com/y-ken/mysql-udf-base64

于 2014-12-01T22:50:20.993 回答
-4

创建表加密（用户名 varchar(20)，密码 varbinary(200)）

插入加密值('raju',aes_encrypt('kumar','key')) select *,cast(aes_decrypt(password,'key') as char(40)) from encrypt where username='raju';

于 2018-05-22T12:16:44.527 回答