Tôi không thể nhận bất kỳ tín dụng nào cho điều này nhưng khi tôi cần một chức năng tương tự, tôi đã tìm thấy điều này (mặc dù không thể nhớ ở đâu) cho một phép ẩn dụ:-
DROP FUNCTION `func_Double_Metaphone`//
CREATE DEFINER=`aaaa`@`%` FUNCTION `func_Double_Metaphone`(st VARCHAR(55)) RETURNS varchar(128) CHARSET utf8
NO SQL
BEGIN
DECLARE length, first, last, pos, prevpos, is_slavo_germanic SMALLINT;
DECLARE pri, sec VARCHAR(45) DEFAULT '';
DECLARE ch CHAR(1);
SET first = 3;
SET length = CHAR_LENGTH(st);
SET last = first + length -1;
SET st = CONCAT(REPEAT('-', first -1), UCASE(st), REPEAT(' ', 5)); SET is_slavo_germanic = (st LIKE '%W%' OR st LIKE '%K%' OR st LIKE '%CZ%'); SET pos = first; IF SUBSTRING(st, first, 2) IN ('GN', 'KN', 'PN', 'WR', 'PS') THEN
SET pos = pos + 1;
END IF;
IF SUBSTRING(st, first, 1) = 'X' THEN
SET pri = 'S', sec = 'S', pos = pos + 1; END IF;
WHILE pos <= last DO
SET prevpos = pos;
SET ch = SUBSTRING(st, pos, 1); CASE
WHEN ch IN ('A', 'E', 'I', 'O', 'U', 'Y') THEN
IF pos = first THEN SET pri = CONCAT(pri, 'A'), sec = CONCAT(sec, 'A'), pos = pos + 1; ELSE
SET pos = pos + 1;
END IF;
WHEN ch = 'B' THEN
IF SUBSTRING(st, pos+1, 1) = 'B' THEN
SET pri = CONCAT(pri, 'P'), sec = CONCAT(sec, 'P'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'P'), sec = CONCAT(sec, 'P'), pos = pos + 1; END IF;
WHEN ch = 'C' THEN
IF (pos > (first + 1) AND SUBSTRING(st, pos-2, 1) NOT IN ('A', 'E', 'I', 'O', 'U', 'Y') AND SUBSTRING(st, pos-1, 3) = 'ACH' AND
(SUBSTRING(st, pos+2, 1) NOT IN ('I', 'E') OR SUBSTRING(st, pos-2, 6) IN ('BACHER', 'MACHER'))) THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSEIF pos = first AND SUBSTRING(st, first, 6) = 'CAESAR' THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'S'), pos = pos + 2; ELSEIF SUBSTRING(st, pos, 4) = 'CHIA' THEN SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSEIF SUBSTRING(st, pos, 2) = 'CH' THEN
IF pos > first AND SUBSTRING(st, pos, 4) = 'CHAE' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'X'), pos = pos + 2; ELSEIF pos = first AND (SUBSTRING(st, pos+1, 5) IN ('HARAC', 'HARIS') OR
SUBSTRING(st, pos+1, 3) IN ('HOR', 'HYM', 'HIA', 'HEM')) AND SUBSTRING(st, first, 5) != 'CHORE' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSEIF SUBSTRING(st, first, 4) IN ('VAN ', 'VON ') OR SUBSTRING(st, first, 3) = 'SCH'
OR SUBSTRING(st, pos-2, 6) IN ('ORCHES', 'ARCHIT', 'ORCHID')
OR SUBSTRING(st, pos+2, 1) IN ('T', 'S')
OR ((SUBSTRING(st, pos-1, 1) IN ('A', 'O', 'U', 'E') OR pos = first)
AND SUBSTRING(st, pos+2, 1) IN ('L', 'R', 'N', 'M', 'B', 'H', 'F', 'V', 'W', ' ')) THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE
IF pos > first THEN
IF SUBSTRING(st, first, 2) = 'MC' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'K'), pos = pos + 2; END IF;
ELSE
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'X'), pos = pos + 2; END IF;
END IF;
ELSEIF SUBSTRING(st, pos, 2) = 'CZ' AND SUBSTRING(st, pos-2, 4) != 'WICZ' THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'X'), pos = pos + 2; ELSEIF SUBSTRING(st, pos+1, 3) = 'CIA' THEN
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'X'), pos = pos + 3; ELSEIF SUBSTRING(st, pos, 2) = 'CC' AND NOT (pos = (first +1) AND SUBSTRING(st, first, 1) = 'M') THEN
IF SUBSTRING(st, pos+2, 1) IN ('I', 'E', 'H') AND SUBSTRING(st, pos+2, 2) != 'HU' THEN
IF (pos = first +1 AND SUBSTRING(st, first) = 'A') OR
SUBSTRING(st, pos-1, 5) IN ('UCCEE', 'UCCES') THEN
SET pri = CONCAT(pri, 'KS'), sec = CONCAT(sec, 'KS'), pos = pos + 3; ELSE
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'X'), pos = pos + 3; END IF;
ELSE
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; END IF;
ELSEIF SUBSTRING(st, pos, 2) IN ('CK', 'CG', 'CQ') THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSEIF SUBSTRING(st, pos, 2) IN ('CI', 'CE', 'CY') THEN
IF SUBSTRING(st, pos, 3) IN ('CIO', 'CIE', 'CIA') THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'X'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'S'), pos = pos + 2; END IF;
ELSE
IF SUBSTRING(st, pos+1, 2) IN (' C', ' Q', ' G') THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 3; ELSE
IF SUBSTRING(st, pos+1, 1) IN ('C', 'K', 'Q') AND SUBSTRING(st, pos+1, 2) NOT IN ('CE', 'CI') THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 1; END IF;
END IF;
END IF;
WHEN ch = 'D' THEN
IF SUBSTRING(st, pos, 2) = 'DG' THEN
IF SUBSTRING(st, pos+2, 1) IN ('I', 'E', 'Y') THEN SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'J'), pos = pos + 3; ELSE
SET pri = CONCAT(pri, 'TK'), sec = CONCAT(sec, 'TK'), pos = pos + 2; END IF;
ELSEIF SUBSTRING(st, pos, 2) IN ('DT', 'DD') THEN
SET pri = CONCAT(pri, 'T'), sec = CONCAT(sec, 'T'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'T'), sec = CONCAT(sec, 'T'), pos = pos + 1; END IF;
WHEN ch = 'F' THEN
IF SUBSTRING(st, pos+1, 1) = 'F' THEN
SET pri = CONCAT(pri, 'F'), sec = CONCAT(sec, 'F'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'F'), sec = CONCAT(sec, 'F'), pos = pos + 1; END IF;
WHEN ch = 'G' THEN
IF SUBSTRING(st, pos+1, 1) = 'H' THEN
IF (pos > first AND SUBSTRING(st, pos-1, 1) NOT IN ('A', 'E', 'I', 'O', 'U', 'Y'))
OR ( pos = first AND SUBSTRING(st, pos+2, 1) != 'I') THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSEIF pos = first AND SUBSTRING(st, pos+2, 1) = 'I' THEN
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'J'), pos = pos + 2; ELSEIF (pos > (first + 1) AND SUBSTRING(st, pos-2, 1) IN ('B', 'H', 'D') )
OR (pos > (first + 2) AND SUBSTRING(st, pos-3, 1) IN ('B', 'H', 'D') )
OR (pos > (first + 3) AND SUBSTRING(st, pos-4, 1) IN ('B', 'H') ) THEN
SET pos = pos + 2; ELSE
IF pos > (first + 2) AND SUBSTRING(st, pos-1, 1) = 'U'
AND SUBSTRING(st, pos-3, 1) IN ('C', 'G', 'L', 'R', 'T') THEN
SET pri = CONCAT(pri, 'F'), sec = CONCAT(sec, 'F'), pos = pos + 2; ELSEIF pos > first AND SUBSTRING(st, pos-1, 1) != 'I' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE
SET pos = pos + 1;
END IF;
END IF;
ELSEIF SUBSTRING(st, pos+1, 1) = 'N' THEN
IF pos = (first +1) AND SUBSTRING(st, first, 1) IN ('A', 'E', 'I', 'O', 'U', 'Y') AND NOT is_slavo_germanic THEN
SET pri = CONCAT(pri, 'KN'), sec = CONCAT(sec, 'N'), pos = pos + 2; ELSE
IF SUBSTRING(st, pos+2, 2) != 'EY' AND SUBSTRING(st, pos+1, 1) != 'Y'
AND NOT is_slavo_germanic THEN
SET pri = CONCAT(pri, 'N'), sec = CONCAT(sec, 'KN'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'KN'), sec = CONCAT(sec, 'KN'), pos = pos + 2; END IF;
END IF;
ELSEIF SUBSTRING(st, pos+1, 2) = 'LI' AND NOT is_slavo_germanic THEN
SET pri = CONCAT(pri, 'KL'), sec = CONCAT(sec, 'L'), pos = pos + 2; ELSEIF pos = first AND (SUBSTRING(st, pos+1, 1) = 'Y'
OR SUBSTRING(st, pos+1, 2) IN ('ES', 'EP', 'EB', 'EL', 'EY', 'IB', 'IL', 'IN', 'IE', 'EI', 'ER')) THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'J'), pos = pos + 2; ELSEIF (SUBSTRING(st, pos+1, 2) = 'ER' OR SUBSTRING(st, pos+1, 1) = 'Y')
AND SUBSTRING(st, first, 6) NOT IN ('DANGER', 'RANGER', 'MANGER')
AND SUBSTRING(st, pos-1, 1) not IN ('E', 'I') AND SUBSTRING(st, pos-1, 3) NOT IN ('RGY', 'OGY') THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'J'), pos = pos + 2; ELSEIF SUBSTRING(st, pos+1, 1) IN ('E', 'I', 'Y') OR SUBSTRING(st, pos-1, 4) IN ('AGGI', 'OGGI') THEN
IF SUBSTRING(st, first, 4) IN ('VON ', 'VAN ') OR SUBSTRING(st, first, 3) = 'SCH'
OR SUBSTRING(st, pos+1, 2) = 'ET' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE
IF SUBSTRING(st, pos+1, 4) = 'IER ' THEN
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'J'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'K'), pos = pos + 2; END IF;
END IF;
ELSEIF SUBSTRING(st, pos+1, 1) = 'G' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 1; END IF;
WHEN ch = 'H' THEN
IF (pos = first OR SUBSTRING(st, pos-1, 1) IN ('A', 'E', 'I', 'O', 'U', 'Y'))
AND SUBSTRING(st, pos+1, 1) IN ('A', 'E', 'I', 'O', 'U', 'Y') THEN
SET pri = CONCAT(pri, 'H'), sec = CONCAT(sec, 'H'), pos = pos + 2; ELSE SET pos = pos + 1; END IF;
WHEN ch = 'J' THEN
IF SUBSTRING(st, pos, 4) = 'JOSE' OR SUBSTRING(st, first, 4) = 'SAN ' THEN
IF (pos = first AND SUBSTRING(st, pos+4, 1) = ' ') OR SUBSTRING(st, first, 4) = 'SAN ' THEN
SET pri = CONCAT(pri, 'H'), sec = CONCAT(sec, 'H'); ELSE
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'H'); END IF;
ELSEIF pos = first AND SUBSTRING(st, pos, 4) != 'JOSE' THEN
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'A'); ELSE
IF SUBSTRING(st, pos-1, 1) IN ('A', 'E', 'I', 'O', 'U', 'Y') AND NOT is_slavo_germanic
AND SUBSTRING(st, pos+1, 1) IN ('A', 'O') THEN
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'H'); ELSE
IF pos = last THEN
SET pri = CONCAT(pri, 'J'); ELSE
IF SUBSTRING(st, pos+1, 1) not IN ('L', 'T', 'K', 'S', 'N', 'M', 'B', 'Z')
AND SUBSTRING(st, pos-1, 1) not IN ('S', 'K', 'L') THEN
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'J'); END IF;
END IF;
END IF;
END IF;
IF SUBSTRING(st, pos+1, 1) = 'J' THEN
SET pos = pos + 2;
ELSE
SET pos = pos + 1;
END IF;
WHEN ch = 'K' THEN
IF SUBSTRING(st, pos+1, 1) = 'K' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 1; END IF;
WHEN ch = 'L' THEN
IF SUBSTRING(st, pos+1, 1) = 'L' THEN
IF (pos = (last - 2) AND SUBSTRING(st, pos-1, 4) IN ('ILLO', 'ILLA', 'ALLE'))
OR ((SUBSTRING(st, last-1, 2) IN ('AS', 'OS') OR SUBSTRING(st, last) IN ('A', 'O'))
AND SUBSTRING(st, pos-1, 4) = 'ALLE') THEN
SET pri = CONCAT(pri, 'L'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'L'), sec = CONCAT(sec, 'L'), pos = pos + 2; END IF;
ELSE
SET pri = CONCAT(pri, 'L'), sec = CONCAT(sec, 'L'), pos = pos + 1; END IF;
WHEN ch = 'M' THEN
IF SUBSTRING(st, pos-1, 3) = 'UMB'
AND (pos + 1 = last OR SUBSTRING(st, pos+2, 2) = 'ER')
OR SUBSTRING(st, pos+1, 1) = 'M' THEN
SET pri = CONCAT(pri, 'M'), sec = CONCAT(sec, 'M'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'M'), sec = CONCAT(sec, 'M'), pos = pos + 1; END IF;
WHEN ch = 'N' THEN
IF SUBSTRING(st, pos+1, 1) = 'N' THEN
SET pri = CONCAT(pri, 'N'), sec = CONCAT(sec, 'N'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'N'), sec = CONCAT(sec, 'N'), pos = pos + 1; END IF;
WHEN ch = 'P' THEN
IF SUBSTRING(st, pos+1, 1) = 'H' THEN
SET pri = CONCAT(pri, 'F'), sec = CONCAT(sec, 'F'), pos = pos + 2; ELSEIF SUBSTRING(st, pos+1, 1) IN ('P', 'B') THEN SET pri = CONCAT(pri, 'P'), sec = CONCAT(sec, 'P'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'P'), sec = CONCAT(sec, 'P'), pos = pos + 1; END IF;
WHEN ch = 'Q' THEN
IF SUBSTRING(st, pos+1, 1) = 'Q' THEN
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'K'), sec = CONCAT(sec, 'K'), pos = pos + 1; END IF;
WHEN ch = 'R' THEN
IF pos = last AND not is_slavo_germanic
AND SUBSTRING(st, pos-2, 2) = 'IE' AND SUBSTRING(st, pos-4, 2) NOT IN ('ME', 'MA') THEN
SET sec = CONCAT(sec, 'R'); ELSE
SET pri = CONCAT(pri, 'R'), sec = CONCAT(sec, 'R'); END IF;
IF SUBSTRING(st, pos+1, 1) = 'R' THEN
SET pos = pos + 2;
ELSE
SET pos = pos + 1;
END IF;
WHEN ch = 'S' THEN
IF SUBSTRING(st, pos-1, 3) IN ('ISL', 'YSL') THEN
SET pos = pos + 1;
ELSEIF pos = first AND SUBSTRING(st, first, 5) = 'SUGAR' THEN
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'S'), pos = pos + 1; ELSEIF SUBSTRING(st, pos, 2) = 'SH' THEN
IF SUBSTRING(st, pos+1, 4) IN ('HEIM', 'HOEK', 'HOLM', 'HOLZ') THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'S'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'X'), pos = pos + 2; END IF;
ELSEIF SUBSTRING(st, pos, 3) IN ('SIO', 'SIA') OR SUBSTRING(st, pos, 4) = 'SIAN' THEN
IF NOT is_slavo_germanic THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'X'), pos = pos + 3; ELSE
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'S'), pos = pos + 3; END IF;
ELSEIF (pos = first AND SUBSTRING(st, pos+1, 1) IN ('M', 'N', 'L', 'W')) OR SUBSTRING(st, pos+1, 1) = 'Z' THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'X'); IF SUBSTRING(st, pos+1, 1) = 'Z' THEN
SET pos = pos + 2;
ELSE
SET pos = pos + 1;
END IF;
ELSEIF SUBSTRING(st, pos, 2) = 'SC' THEN
IF SUBSTRING(st, pos+2, 1) = 'H' THEN
IF SUBSTRING(st, pos+3, 2) IN ('OO', 'ER', 'EN', 'UY', 'ED', 'EM') THEN
IF SUBSTRING(st, pos+3, 2) IN ('ER', 'EN') THEN
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'SK'), pos = pos + 3; ELSE
SET pri = CONCAT(pri, 'SK'), sec = CONCAT(sec, 'SK'), pos = pos + 3; END IF;
ELSE
IF pos = first AND SUBSTRING(st, first+3, 1) not IN ('A', 'E', 'I', 'O', 'U', 'Y') AND SUBSTRING(st, first+3, 1) != 'W' THEN
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'S'), pos = pos + 3; ELSE
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'X'), pos = pos + 3; END IF;
END IF;
ELSEIF SUBSTRING(st, pos+2, 1) IN ('I', 'E', 'Y') THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'S'), pos = pos + 3; ELSE
SET pri = CONCAT(pri, 'SK'), sec = CONCAT(sec, 'SK'), pos = pos + 3; END IF;
ELSEIF pos = last AND SUBSTRING(st, pos-2, 2) IN ('AI', 'OI') THEN
SET sec = CONCAT(sec, 'S'), pos = pos + 1; ELSE
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'S'); IF SUBSTRING(st, pos+1, 1) IN ('S', 'Z') THEN
SET pos = pos + 2;
ELSE
SET pos = pos + 1;
END IF;
END IF;
WHEN ch = 'T' THEN
IF SUBSTRING(st, pos, 4) = 'TION' THEN
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'X'), pos = pos + 3; ELSEIF SUBSTRING(st, pos, 3) IN ('TIA', 'TCH') THEN
SET pri = CONCAT(pri, 'X'), sec = CONCAT(sec, 'X'), pos = pos + 3; ELSEIF SUBSTRING(st, pos, 2) = 'TH' OR SUBSTRING(st, pos, 3) = 'TTH' THEN
IF SUBSTRING(st, pos+2, 2) IN ('OM', 'AM') OR SUBSTRING(st, first, 4) IN ('VON ', 'VAN ')
OR SUBSTRING(st, first, 3) = 'SCH' THEN
SET pri = CONCAT(pri, 'T'), sec = CONCAT(sec, 'T'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, '0'), sec = CONCAT(sec, 'T'), pos = pos + 2; END IF;
ELSEIF SUBSTRING(st, pos+1, 1) IN ('T', 'D') THEN
SET pri = CONCAT(pri, 'T'), sec = CONCAT(sec, 'T'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'T'), sec = CONCAT(sec, 'T'), pos = pos + 1; END IF;
WHEN ch = 'V' THEN
IF SUBSTRING(st, pos+1, 1) = 'V' THEN
SET pri = CONCAT(pri, 'F'), sec = CONCAT(sec, 'F'), pos = pos + 2; ELSE
SET pri = CONCAT(pri, 'F'), sec = CONCAT(sec, 'F'), pos = pos + 1; END IF;
WHEN ch = 'W' THEN
IF SUBSTRING(st, pos, 2) = 'WR' THEN
SET pri = CONCAT(pri, 'R'), sec = CONCAT(sec, 'R'), pos = pos + 2; ELSEIF pos = first AND (SUBSTRING(st, pos+1, 1) IN ('A', 'E', 'I', 'O', 'U', 'Y')
OR SUBSTRING(st, pos, 2) = 'WH') THEN
IF SUBSTRING(st, pos+1, 1) IN ('A', 'E', 'I', 'O', 'U', 'Y') THEN
SET pri = CONCAT(pri, 'A'), sec = CONCAT(sec, 'F'), pos = pos + 1; ELSE
SET pri = CONCAT(pri, 'A'), sec = CONCAT(sec, 'A'), pos = pos + 1; END IF;
ELSEIF (pos = last AND SUBSTRING(st, pos-1, 1) IN ('A', 'E', 'I', 'O', 'U', 'Y'))
OR SUBSTRING(st, pos-1, 5) IN ('EWSKI', 'EWSKY', 'OWSKI', 'OWSKY')
OR SUBSTRING(st, first, 3) = 'SCH' THEN
SET sec = CONCAT(sec, 'F'), pos = pos + 1; ELSEIF SUBSTRING(st, pos, 4) IN ('WICZ', 'WITZ') THEN
SET pri = CONCAT(pri, 'TS'), sec = CONCAT(sec, 'FX'), pos = pos + 4; ELSE SET pos = pos + 1;
END IF;
WHEN ch = 'X' THEN
IF not(pos = last AND (SUBSTRING(st, pos-3, 3) IN ('IAU', 'EAU')
OR SUBSTRING(st, pos-2, 2) IN ('AU', 'OU'))) THEN
SET pri = CONCAT(pri, 'KS'), sec = CONCAT(sec, 'KS'); END IF;
IF SUBSTRING(st, pos+1, 1) IN ('C', 'X') THEN
SET pos = pos + 2;
ELSE
SET pos = pos + 1;
END IF;
WHEN ch = 'Z' THEN
IF SUBSTRING(st, pos+1, 1) = 'H' THEN
SET pri = CONCAT(pri, 'J'), sec = CONCAT(sec, 'J'), pos = pos + 1; ELSEIF SUBSTRING(st, pos+1, 3) IN ('ZO', 'ZI', 'ZA')
OR (is_slavo_germanic AND pos > first AND SUBSTRING(st, pos-1, 1) != 'T') THEN
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'TS'); ELSE
SET pri = CONCAT(pri, 'S'), sec = CONCAT(sec, 'S'); END IF;
IF SUBSTRING(st, pos+1, 1) = 'Z' THEN
SET pos = pos + 2;
ELSE
SET pos = pos + 1;
END IF;
ELSE
SET pos = pos + 1; END CASE;
IF pos = prevpos THEN
SET pos = pos +1;
SET pri = CONCAT(pri,'<didnt incr>'); END IF;
END WHILE;
IF pri != sec THEN
SET pri = CONCAT(pri, ';', sec);
END IF;
RETURN (pri);
END
Tôi cũng cần một hàm levenshtein và cố gắng sắp xếp một trong những hàm đó, nhưng hiệu suất cao đến mức (khi so sánh các giá trị từ nhiều hàng) nên việc đọc các hàng và sử dụng hàm php được tích hợp trong hàm levenshtein nhanh hơn rất nhiều.
