title: Procedure to loop through comma separated string is not working
body: <p>I have corrected the code with the help of answer given in stack overflow. I want to loop through the comma separated string of Ids but not able to do so. Below given procedure only updates first record and not updating other records. What corrections are required so that I can loop through comma separated string.
  This is the code for my SP</p>
  
  <pre><code>BEGIN
    DECLARE strLen    INT DEFAULT 0;
    DECLARE SubStrLen INT DEFAULT 0;
  
    IF strIDs IS NULL THEN
     SET strIDs = '';
    END IF;
  
  do_this:
  LOOP
  SET strLen = LENGTH(strIDs);
  
  UPDATE TestTable SET status = 'C' WHERE Id = SUBSTRING_INDEX(strIDs, ',', 1);
  
  SET SubStrLen = LENGTH(SUBSTRING_INDEX(strIDs, ',', 1));
  SET strIDs = MID(strIDs, SubStrLen, strLen);
  
  IF strIDs = NULL THEN
    LEAVE do_this;
  END IF;
  END LOOP do_this;
  END
  </code></pre>
  
  <p>The code is as provided in the answers for this post.</p>
  
  <p>I tried with find_in_set() function but it works only if I pass ids start from beginning and not working if I pass Ids randomly.
  This is my script for the table</p>
  
  <pre><code>CREATE TABLE `testtable` (
  </code></pre>
  
  <p><code>Id</code> int(11) DEFAULT NULL,
      <code>Status</code> varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL
      ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;</p>
  
  <pre><code>-- ----------------------------
  -- Records of testtable
  -- ----------------------------
  INSERT INTO `testtable` VALUES ('1', 'O');
  INSERT INTO `testtable` VALUES ('2', 'O');
  INSERT INTO `testtable` VALUES ('3', 'O');
  INSERT INTO `testtable` VALUES ('4', 'O');
  INSERT INTO `testtable` VALUES ('5', 'O');
  </code></pre>
  
  <p>This is the stored procedure
      BEGIN
        UPDATE TestTable SET status = 'C' WHERE Id = FIND_IN_SET(Id, strIDs);
      END</p>
  
  <p>strIds is varchar type.</p>
  
  <p>Now try @strIDs='2'</p>