Return only the digits from a string:
SET GLOBAL log_bin_trust_function_creators=1;
DROP FUNCTION IF EXISTS digits;
DELIMITER |
CREATE FUNCTION digits( str CHAR(32) ) RETURNS CHAR(32)
BEGIN
DECLARE i, len SMALLINT DEFAULT 1;
DECLARE ret CHAR(32) DEFAULT '';
DECLARE c CHAR(1);
SET len = CHAR_LENGTH( str );
REPEAT
BEGIN
SET c = MID( str, i, 1 );
IF c BETWEEN '0' AND '9' THEN
SET ret=CONCAT(ret,c);
END IF;
SET i = i + 1;
END;
UNTIL i > len END REPEAT;
RETURN ret;
END |
DELIMITER ;
SELECT digits('123ab45cde6789fg');
+----------------------------+
| digits('123ab45cde6789fg') |
+----------------------------+
| 123456789 |
+----------------------------+
Return only the alphabetic characters from a string:
DROP FUNCTION IF EXISTS alphas;
DELIMITER |
CREATE FUNCTION alphas( str CHAR(32) ) RETURNS CHAR(16)
BEGIN
DECLARE i, len SMALLINT DEFAULT 1;
DECLARE ret CHAR(32) DEFAULT '';
DECLARE c CHAR(1);
SET len = CHAR_LENGTH( str );
REPEAT
BEGIN
SET c = MID( str, i, 1 );
IF c REGEXP '[[:alpha:]]' THEN
SET ret=CONCAT(ret,c);
END IF;
SET i = i + 1;
END;
UNTIL i > len END REPEAT;
RETURN ret;
END |
DELIMITER ;
SELECT alphas('123ab45cde6789fg');
+----------------------------+
| alphas('123ab45cde6789fg') |
+----------------------------+
| abcdefg |
+----------------------------+
|
|