使用 C# 连接到数据库

Question

I am trying to connect to a database for my Login wpf.

SqlConnectionStringBuilder mConnectionBuilder = new SqlConnectionStringBuilder
{
    DataSource = @"(LocalDB)\MSSQLLocalDB",
    InitialCatalog = "UserData"               
};

using (SqlConnection mConnection = new SqlConnection(mConnectionBuilder.ConnectionString))
{
    SqlCommand mCommand = new SqlCommand
    {
        Connection = mConnection,
        CommandText = "Select Id, Username, E-Mail, Password from Users"
    };

    if (mConnection.State == ConnectionState.Closed)
    {
        mConnection.Open();
    }

    using (SqlDataReader mReader = mCommand.ExecuteReader())
    {
        while (mReader.Read())
        {
            string mUsername = Convert.ToString(mReader.GetValue(1));
            string mPassword = Convert.ToString(mReader.GetValue(2));

            if (txtLoginUsername.Text == mUsername && txtLoginPassword.Text == mPassword)
            {
                loginSuccessful = true;
            }
            else
            {
                MessageBox.Show("Wrong username or password");
            }
        }
    }
}

I created the database in Visual Studio and named it UserData. But at mConnection.Open() i get an SqlException "Cannot open database "UserData" requested by the login. The login failed. Login failed for user (myUserName)". I know there are different ways to use SQL with C# but I want it to work that way really hard because I waisted way too much time to find a solution for this problem. I hope i can get some helpful information here:)

Answer 1

String connetionString = null;
SqlConnection cnn;

connetionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password"
cnn = new SqlConnection(connetionString);
try
{
    cnn.Open();
    MessageBox.Show ("Connection Open ! ");
    cnn.Close();
}
catch (Exception ex)
{
    MessageBox.Show("Can not open connection ! ");
}