MySQL Stored Procedure Error

First question... what exactly is the syntax error that it throws up?

I don't know much about stored procedures but I had a bit of a play by trying to create your stored procedure line by line and dealing with the error messages 1 at a time.

In order to get it to compile I had to re-order your DECLARE statements and change your SELECT statements from :

Bank_URL = Select BankURL From

to

SELECT BankURL INTO Bank_URL FROM

Try the below code.  I think it will work.

DELIMITER $$

DROP PROCEDURE IF EXISTS `test`.`RefineData` $$
CREATE PROCEDURE `test`.`RefineData` ()


BEGIN

DECLARE R_N_F INT DEFAULT 0;
DECLARE Bank_Name VARCHAR(100) DEFAULT "";
DECLARE Bank_URL VARCHAR(100) DEFAULT NULL;
DECLARE Bank_Login_URL VARCHAR(100) DEFAULT NULL;
DECLARE BankNames CURSOR FOR SELECT * FROM Temp;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET R_N_F = 1;

CREATE TEMPORARY TABLE Temp AS SELECT DISTINCT BankName FROM `BankList`;

OPEN BankNames;
     allBanks: LOOP
               FETCH BankNames INTO Bank_Name;
               IF R_N_F THEN
                  LEAVE allBanks;
               END IF;

               SELECT BankURL INTO Bank_URL FROM (SELECT DISTINCT BankURL, Length(BankURL) AS Rank FROM BankList WHERE BankName = Bank_Name ORDER BY Rank ASC LIMIT 1) AS a;
               SELECT BankURL INTO Bank_Login_URL FROM (SELECT DISTINCT BankURL, Length(BankURL) AS Rank FROM BankList WHERE BankName = Bank_Name ORDER BY Rank DESC LIMIT 1) As b;
               INSERT INTO `RefinedBankList` SELECT Bank_Name, Bank_URL, Bank_Login_URL;
     END LOOP allBanks;
CLOSE BankNames;

DROP TABLE Temp;

END $$

DELIMITER ;

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The syntax error is :
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DECLARE R_N_F INTEGER DEFAULT 0;
DECLARE BankNames CURSOR FOR SELECT * FROM Tem' at line 4

The more refined code is below having still same problem :(

DELIMITER $$

DROP PROCEDURE IF EXISTS `bankman`.`RefineData` $$
CREATE PROCEDURE `bankman`.`RefineData` ()
BEGIN
  Create Temporary Table Temp As (Select Distinct BankName FROM BankList);
  DECLARE R_N_F INTEGER DEFAULT 0;
  DECLARE BankNames CURSOR FOR SELECT * FROM Temp;
  DECLARE Bank_Name VARCHAR(100) DEFAULT "";
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET R_N_F = 1;
  OPEN BankNames;
    allBanks: LOOP
      FETCH BankNames INTO Bank_Name;
      IF R_N_F THEN
        LEAVE allStudents;
      END IF;
      DECLARE Bank_URL VARCHAR(100) DEFAULT NULL;
      DECLARE Bank_Login_URL VARCHAR(100) DEFAULT NULL;
      Select BankURL INTO Bank_URL From (Select Distinct BankURL, Length(BankURL) As Rank From BankList Where BankName = Bank_Name Order By Rank ASC Limit 1) As a;
      Select BankURL INTO Bank_Login_URL From (Select Distinct BankURL, Length(BankURL) As Rank From BankList Where BankName = Bank_Name Order By Rank DESC Limit 1) As b;
      Insert Into RefinedBankList Select Bank_Name, Bank_URL, Bank_Login_URL;
    END LOOP allBanks;
  CLOSE BankNames;
Drop Table Temp;

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Latest Code below:

DELIMITER $$

DROP PROCEDURE IF EXISTS `bankman`.`RefineData` $$
CREATE PROCEDURE `bankman`.`RefineData` ()
BEGIN
  Create Temporary Table Temp As (Select Distinct BankName FROM BankList);
  DECLARE R_N_F INTEGER DEFAULT 0;
  DECLARE BankNames CURSOR FOR SELECT * FROM Temp;
  DECLARE Bank_Name VARCHAR(100) DEFAULT "";
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET R_N_F = 1;
  OPEN BankNames;
    allBanks: LOOP
      FETCH BankNames INTO Bank_Name;
      IF R_N_F THEN
        LEAVE allStudents;
      END IF;
      DECLARE Bank_URL VARCHAR(100) DEFAULT NULL;
      DECLARE Bank_Login_URL VARCHAR(100) DEFAULT NULL;
      Select BankURL INTO Bank_URL From (Select Distinct BankURL, Length(BankURL) As Rank From BankList Where BankName = Bank_Name Order By Rank ASC Limit 1) As a;
      Select BankURL INTO Bank_Login_URL From (Select Distinct BankURL, Length(BankURL) As Rank From BankList Where BankName = Bank_Name Order By Rank DESC Limit 1) As b;
      Insert Into RefinedBankList Select Bank_Name, Bank_URL, Bank_Login_URL;
    END LOOP allBanks;
  CLOSE BankNames;
Drop Table Temp;
END $$

DELIMITER ;

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I got around that error by re-ordering the DECLARE statements to be at the top.  Look at my solution again.