MySQL SELECT with URL Decode

I feel like its important to answer the original question ( regardless of alternatives ), mainly because its been asked and is a valid question:

The short answer: You cannot.

There is no native SQL function for decoding URL encoded strings.

The long answer: You need to write a custom SQL function:

Encode / Decode MySQL functions: http://www.dzone.com/snippets/urlencodeurldecode-mysql

The best answer: Anything URL Encoded can be stored as UTF8.

Change your tables to UTF8 by: dumping, replacing "latin1" with "utf8", and importing. Then run a script ( just once ) such as PHP, Python, or Rails to decode your column and store it back. And now you're ready to use your DB as it was intended. No overhead.

Python code to do this:

import urllib

import MySQLdb

def decode():

  con = MySQLdb.Connect(host="127.0.0.1", port=3306, user="root", passwd="", db="hostip")
  cursor = con.cursor()

  cursor.execute("SELECT city, name FROM cityByCountry")

  for row in cursor.fetchall():
    print row
    cursor.execute("UPDATE cityByCountry SET name=%s WHERE city=%s", (urllib.unquote(row[1]), row[0]))

if __name__ == "__main__":
  decode()

If anyone is still looking for a mysql decode function:

DROP TABLE IF EXISTS urlcodemap;

CREATE TABLE `urlcodemap` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `encoded` VARCHAR(128) NOT NULL,
  `decoded` VARCHAR(128) NOT NULL,
  UNIQUE KEY urlcodemapUIdx1(encoded),
  PRIMARY KEY (`id`)  
) ENGINE=INNODB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

-- Table that contains the list of encode\decode.
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%20"," ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%21","!");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%22","""");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%23","#");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%24","$");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%25","%");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%26","&");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%27","'");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%28","(");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%29",")");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%2A","*");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%2B","+");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%2C",",");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%2D","-");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%2E",".");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%2F","/");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%30","0");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%31","1");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%32","2");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%33","3");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%34","4");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%35","5");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%36","6");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%37","7");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%38","8");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%39","9");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%3A",":");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%3B",";");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%3C","<");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%3D","=");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%3E",">");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%3F","?");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%40","@");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%41","A");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%42","B");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%43","C");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%44","D");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%45","E");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%46","F");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%47","G");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%48","H");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%49","I");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%4A","J");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%4B","K");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%4C","L");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%4D","M");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%4E","N");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%4F","O");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%50","P");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%51","Q");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%52","R");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%53","S");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%54","T");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%55","U");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%56","V");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%57","W");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%58","X");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%59","Y");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%5A","Z");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%5B","[");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%5C","\\");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%5D","]");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%5E","^");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%5F","_");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%60","`");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%61","a");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%62","b");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%63","c");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%64","d");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%65","e");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%66","f");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%67","g");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%68","h");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%69","i");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%6A","j");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%6B","k");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%6C","l");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%6D","m");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%6E","n");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%6F","o");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%70","p");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%71","q");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%72","r");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%73","s");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%74","t");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%75","u");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%76","v");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%77","w");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%78","x");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%79","y");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%7A","z");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%7B","{");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%7C","|");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%7D","}");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%7E","~");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%80","`");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%82","‚");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%83","ƒ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%84","„");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%85","…");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%86","†");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%87","‡");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%88","ˆ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%89","‰");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%8A","Š");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%8B","‹");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%8C","Œ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%8E","Ž");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%91","‘");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%92","’");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%93","“");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%94","”");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%95","•");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%96","–");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%97","—");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%98","˜");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%99","™");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%9A","š");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%9B","›");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%9C","œ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%9E","ž");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%9F","Ÿ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A1","¡");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A2","¢");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A3","£");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A4","¤");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A5","¥");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A6","¦");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A7","§");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A8","¨");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%A9","©");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%AA","ª");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%AB","«");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%AC","¬");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%AE","®");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%AF","¯");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B0","°");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B1","±");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B2","²");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B3","³");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B4","´");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B5","µ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B6","¶");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B7","·");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B8","¸");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%B9","¹");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%BA","º");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%BB","»");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%BC","¼");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%BD","½");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%BE","¾");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%BF","¿");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C0","À");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C1","Á");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C2","Â");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C3","Ã");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C4","Ä");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C5","Å");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C6","Æ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C7","Ç");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C8","È");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%C9","É");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%CA","");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%CB","Ë");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%CC","Ì");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%CD","Í");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%CE","Î");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%CF","Ï");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D0","Ð");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D1","Ñ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D2","Ò");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D3","Ó");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D4","Ô");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D5","Õ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D6","Ö");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D7","×");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D8","Ø");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%D9","Ù");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%DA","Ú");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%DB","Û");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%DC","Ü");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%DD","Ý");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%DE","Þ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%DF","ß");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E0","à");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E1","á");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E2","â");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E3","ã");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E4","ä");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E5","å");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E6","æ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E7","ç");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E8","è");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%E9","é");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%EA","ê");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%EB","ë");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%EC","ì");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%ED","í");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%EE","î");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%EF","ï");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F0","ð");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F1","ñ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F2","ò");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F3","ó");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F4","ô");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F5","õ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F6","ö");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F7","÷");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F8","ø");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%F9","ù");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%FA","ú");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%FB","û");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%FC","ü");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%FD","ý");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%FE","þ");
INSERT INTO urlcodemap (encoded,decoded) VALUES ("%FF","ÿ");

DELIMITER $$

DROP FUNCTION IF EXISTS `URLDECODER`$$

CREATE FUNCTION `URLDECODER`(str VARCHAR(4096) CHARSET utf8) RETURNS VARCHAR(4096) DETERMINISTIC
BEGIN
               DECLARE X  INT;               
               DECLARE chr VARCHAR(256);
               DECLARE chrto VARCHAR(256);
               DECLARE result VARCHAR(4096);
               SET X = 1;
               WHILE X  <= (SELECT MAX(id) FROM urlcodemap) DO
                   SET chr = (SELECT `encoded` FROM urlcodemap WHERE id = X);
                   SET chrto = (SELECT `decoded` FROM urlcodemap WHERE id = X);                
                           SET str = REPLACE(str,chr,chrto);
                           SET  X = X + 1;                           
               END WHILE;
               RETURN str;
       END$$

DELIMITER ;    

Usage example

SELECT urldecoder('http://testing.com/questions/7031469/is%20this%20working');