C# Set variable on MySQL query

Question

i am writing C# function now, which must return me user password. All is fine, but than i am trying to compile this project, VS telling me about unassigned variable.

string sqlLoginCheck (string userId)
    {
        string database, host, user, pass, sqlParams, sqlQuery;
        string resultPassword;

        database = "db";
        host = "localhost";
        user = "root";
        pass = "....";

        sqlParams = "Database=" + database + ";Data Source=" + host + ";User Id=" + user + ";Password=" + pass;
        sqlQuery = "SELECT `id`, `name`, `pass` FROM `users` WHERE name = '" + userId + "' LIMIT 1";

        MySqlConnection sqlConnection = new MySqlConnection(sqlParams);
        MySqlCommand sqlCommand = new MySqlCommand(sqlQuery, sqlConnection);

        // Выполняем
        try
        {
            sqlConnection.Open();

            MySqlDataReader sqlReader = sqlCommand.ExecuteReader();

            if (sqlReader.HasRows)
            {
                while (sqlReader.Read())
                {
                    resultPassword = sqlReader[2].ToString();
                }
            }
            else
            {
                resultPassword = "";
            }
        }

        catch (MySqlException sqlError)
        {
            errorMessage.Text = "Ошибка: " + sqlError.Message;

            FileInfo errorLog = new FileInfo("errorLog.txt");

            if (errorLog.Exists == false)
            {
                FileStream errorFs = errorLog.Create();
                errorFs.Close();
            }

            StreamWriter errorSw = errorLog.AppendText();

            errorSw.WriteLine(DateTime.Now + " | " + sqlError.Message);
            errorSw.Close();
        }

        finally
        {
            sqlConnection.Close();
        }

        return resultPassword;

    }

Here i can't return resultPassword, because variable is unassigned :|

Ivan Golović · Accepted Answer · 2012-07-03 10:01:08Z

2

Declare this variable as

string resultPassword = null;

Or you can declare it as

string resultPassword = String.Empty;

in that case you don't really need

else
{
            resultPassword = "";
}

because default value for password has already been set at declaration.

edited Jul 3, 2012 at 10:01

answered Jul 3, 2012 at 9:54

Ivan Golović

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1 Comment

Littlebobbydroptables Over a year ago

Thanks you and all who answered, this helped!

Alberto De Caro · Accepted Answer · 2012-07-03 09:55:08Z

1

The resultPassword is declared in the function body, but it is initialized only inside the try block: so in case of exception, the variable will be unassigned.

Initialize the variable outside the try-catch block.

Some details here.

answered Jul 3, 2012 at 9:55

Alberto De Caro

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Comments

MBen · Accepted Answer · 2012-07-03 09:55:33Z

0

The compiler sees that there is a chance that resultPassword never gets assigned (if you go into the Catch or Finally. Just do :

string resultPassword = "";

in the declaration

answered Jul 3, 2012 at 9:55

MBen

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Comments

Alan Bradbury · Accepted Answer · 2012-07-03 09:55:40Z

0

It's because there is a root through the method where resultPassword is never assigned a value. As others have said declare:

string resultPassword = null;

answered Jul 3, 2012 at 9:55

Alan Bradbury

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BugFinder · Accepted Answer · 2012-07-03 09:55:59Z

0

I would suggest

string resultPassword = "";

then if you need to set to not found, actually set it to say "** not found **" or something. As it stands you have paths down your code where the variable isnt set - eg it enters the catch area.

answered Jul 3, 2012 at 9:55

BugFinder

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