title: Why this mysql function return null
body: <pre><code>DELIMITER $$
  
  USE `healthsystem`$$
  
  DROP FUNCTION IF EXISTS `GetBillingProviderInfo`$$
  
  CREATE DEFINER=`root`@`localhost` FUNCTION `GetBillingProviderInfo`(claimID LONG, claimInsCode VARCHAR(50)) RETURNS CHAR(50) DETERMINISTIC
  BEGIN
      DECLARE varReturnValue                      VARCHAR(5000);
      DECLARE varProviderCode                     VARCHAR(20);
      DECLARE varLocationCode                     VARCHAR(20);
      DECLARE varFindCase                     VARCHAR(10);
      DECLARE varbillwithNPI                              VARCHAR(2);    
      DECLARE varoverrideGroupNPI                         BIT(1);        
      DECLARE varoverrideGroupNPIValue                    VARCHAR(30);   
      DECLARE varbillwithSSN                              VARCHAR(20);   
      DECLARE varoverrideTaxID                            BIT(1);        
      DECLARE varoverrideTaxIDValue                       VARCHAR(30);   
      DECLARE varoverrideName                             BIT(1);        
      DECLARE varoverrideBillingNameValue                 VARCHAR(50);  
      DECLARE varoverrideBillingAddress                   BIT(1);        
      DECLARE varoverrideAddress1                         VARCHAR(255);  
      DECLARE varoverrideAddress2                         VARCHAR(255);  
      DECLARE varoverrideCity                             VARCHAR(255);  
      DECLARE varoverrideState                            VARCHAR(2);    
      DECLARE varoverrideZipCode                          VARCHAR(20);   
      DECLARE varBoxNo33BillingName                   VARCHAR(50);
      DECLARE varBoxNo33Address1                  VARCHAR(50);
      DECLARE varBoxNo33Address2                  VARCHAR(50);
      DECLARE varBoxNo33City                      VARCHAR(20);
      DECLARE varBoxNo33State                     VARCHAR(2);
      DECLARE varBoxNo33ZipCode                   VARCHAR(10);
      DECLARE varLastName                     VARCHAR(100);
      DECLARE varFirstName                        VARCHAR(100);
      DECLARE varMiddleName                       VARCHAR(100);
      DECLARE varPracticeID                       BIGINT;
      DECLARE varrecordCount                      INT;
      RETURN  varReturnValue;
  
  
  
       RETURN CONCAT('Hello, ',s,'!');
  
  
      END$$
  
  DELIMITER ;
  
  SELECT GetBillingProviderInfo(51,'MEDICARE-GHI');
  </code></pre>