C#

DELIMITER $$

USE `generalledger`$$

DROP FUNCTION IF EXISTS `fLogin_Check`$$

CREATE DEFINER=`root`@`localhost` 
FUNCTION `fLogin_Check`
(mUserName   VARCHAR(50),mUserPass VARCHAR(40),mUserKey VARCHAR(40)) RETURNS INT
BEGIN
DECLARE mCount INT;

SELECT COUNT(*) INTO mCount FROM userMaster    
WHERE userName = mUserName
AND AES_DECRYPT(userPass, mUserKey) = UPPER( mUserPass);

IF mCount > 0 THEN
RETURN 1;
ELSE
RETURN  0;
END IF;
END$$

DELIMITER ;

public int CheckUser(string mUserName, string mPass, string mKey)
{
    oCn = da.GetConnection();

    int res;

    if (oCn == null)
    {
        oCn.Open();
    }

    sInsProcName = "fLogin_Check";
    insertcommand = new MySqlCommand(sInsProcName, oCn);
    insertcommand.CommandType = CommandType.StoredProcedure;
    insertcommand.Parameters.Add(new MySqlParameter("mRes", MySqlDbType.Int32, 0));
    insertcommand.Parameters["mRes"].Direction = ParameterDirection.ReturnValue;
    insertcommand.Parameters.Add("mUserName", MySqlDbType.VarChar, 50, mUserName);
    insertcommand.Parameters.Add("mUserPass", MySqlDbType.VarChar, 40, mPass);
    insertcommand.Parameters.Add("mUserKey", MySqlDbType.VarChar, 40);
    insertcommand.Parameters["mUserKey"].Value = mKey;

    res = insertcommand.ExecuteNonQuery();
    //res = int.Parse(insertcommand.Parameters["mRes"].Value.ToString());

    return (res);

    oCn.Close();
}

public static class Globals
{
    public static string userName;
    public static string userPass;
    public const string sKey = "AHMEDFINANCEICMAP1122";
}

private void btnCheck_Click(object sender, EventArgs e)
{
    Globals.userName = txtUser.Text.ToString();
    Globals.userPass = txtPass.Text.ToString();

    if (fUser.CheckUser(Globals.userName, Globals.userPass, Globals.sKey) == 0)
    {
        MessageBox.Show("Invalid Username or Password.");
    }
    else
    {
        MessageBox.Show("Login Successfull");
    }
}

SELECT fLogin_Check("AHMED","AHMED1981","AHMEDFINANCEICMAP1122") FROM userMaster