delimiter
创建函数之前不要忘记更改。
DELIMITER $$CREATE FUNCTION LEVENSHTEIN( s1 CHAr(255), s2 CHAr(255)) RETURNS int(3) DETERMINISTICBEGIN DECLARE s1_len, s2_len, i, j, c, c_temp, cost INT; DECLARE s1_char CHAr(255); DECLARE cv0, cv1 CHAr(255); SET s1_len = LENGTH(s1); SET s2_len = LENGTH(s2); SET cv1 = 0x00; SET j = 1; SET i = 1; SET c = 0; IF s1 = s2 THEN RETURN 0; ELSE IF s1_len = 0 THEN RETURN s2_len; ELSE IF s2_len = 0 THEN RETURN s1_len; ELSE WHILE j <= s2_len DOSET c = c + 1;IF s1_char = SUBSTRINg(s2, j, 1) THEN SET cost = 0; ELSE SET cost = 1;END IF;SET c_temp = CONv(HEx(SUBSTRINg(cv1, j, 1)), 16, 10) + cost; SET c_temp = CONv(HEx(SUBSTRINg(cv1, j+1, 1)), 16, 10) + 1; IF c > c_temp THEN SET c = c_temp; END IF; SET cv0 = CONCAt(cv0, UNHEx(HEx(c))), j = j + 1; END WHILE; SET cv1 = cv0, i = i + 1; END WHILE; END IF; RETURN c;END$$DELIMITER ;
