DataReader is not returning results from a MySQL Stored Proc

Question

I have a stored proc in MySQL (5.5) that I'm calling from a C# application (using MySQL.Data v6.4.4.0).

I have a bunch of other procs that work fine, but this is not returning any results, the data reader says the result set is empty. The proc does a couple of inserts & an update inside a transaction then selects 2 local variables to return. The inserts & update are happening, but the select is not returning.

When I run the proc manually it works, gives a single row with the two fields, but the data reader is empty.

This is the proc:

CREATE DEFINER=`root`@`localhost` PROCEDURE `File_UpdateFile`(IN siteId INT, IN fileId INT, IN description VARCHAR(100), IN folderId INT, IN fileSize INT, IN filePath VARCHAR(100), IN userId INT)
BEGIN
    START TRANSACTION;  
        SELECT MAX(v.versionNumber) + 1 INTO @versionNumber 
        FROM `file_version` v 
        JOIN `file` f ON (v.fileId = f.fileId) 
        WHERE v.fileId = fileId AND f.siteId = siteId;

        INSERT INTO `file_version` (fileId, versionNumber, description, fileSize, filePath, uploadedOn, uploadedBy, fileVersionState)
        VALUES (fileId, @versionNumber, description, fileSize, filePath, NOW(), userId, 0);

        INSERT INTO filehistory (fileId, `action`, userId, createdOn) VALUES (fileId, 'UPDATE', userId, NOW());

        UPDATE `file` f SET f.checkedOutBy = NULL WHERE f.fileId = fileId;

    COMMIT;
    SELECT fileId, @versionNumber `versionNumber`;


    END$$

I'm calling the proc using Dapper, but I've debugged into the SqlMapper class and I can see that the reader is not returning anything.

Answer 1

As a workaround - if you need to retrieve just a scalar value from a stored function, you can do it through the OUT parameters.

Glenn, I tried to understand the reason and found just this way. Actually we use another components, you may see the result of multiple result-set in our GUI tool (free express version of dbForge Studio).