base64 mysql with tables temporary

-- --------------------------------------------------------------------------------
-- Routine DDL
-- Note: comments before and after the routine body will not be stored by the server
-- --------------------------------------------------------------------------------
DELIMITER $$

CREATE DEFINER=`root`@`localhost` 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;

CREATE TEMPORARY TABLE base64_data (c CHAR(1) BINARY, val TINYINT)ENGINE=MEMORY;
        INSERT INTO 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) ;


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 CHAR(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 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;

 DROP TEMPORARY TABLE IF EXISTS base64_data;

        RETURN ret;

END