MySQL 8.0

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CREATE TABLE IF NOT EXISTS t1 (
   id_ INTEGER  AUTO_INCREMENT NOT NULL PRIMARY KEY,
   name VARCHAR(100) NOT NULL);
   
INSERT INTO t1 (name) VALUES
('Dummy Gummy 1'), ('Dummy 2'), ('Dummy 3'), ('Dummy 4'),
('Dummy 5'), ('Dummy 6'), ('Dummy 7'), ('Dummy 8')
CREATE Function getfirsst(_text VARCHAR(100))
RETURNS VARCHAR(20)
DETERMINISTIC
BEGIN
DECLARE inipos INTEGER;
DECLARE endpos INTEGER;
DECLARE maxlen INTEGER;
DECLARE item VARCHAR(100);
DECLARE result VARCHAR(100) DEFAULT '';
DECLARE delim VARCHAR(1);

SET delim = ' ';
SET inipos = 1;
SET _text = CONCAT(_text, delim);
SET maxlen = LENGTH(_text);

REPEAT
    SET endpos = LOCATE(delim, _text, inipos);
    SET item =  SUBSTR(_text, inipos, endpos - inipos);
    IF item <> '' AND item IS NOT NULL THEN
        IF item REGEXP '^[0-9]+$' THEN
            SET result :=  CONCAT(result,item);
        ELSE
            SET result :=  CONCAT(result,LEFT(item,1));
        END IF;
        
    END IF;
    SET inipos = endpos + 1;
UNTIL inipos >= maxlen END REPEAT;
RETURN result;
END
SELECT getfirsst(name) FROM t1


getfirsst(name)


DG1

D2

D3

D4

D5

D6

D7

D8