未提供参数化查询***

Question

我遇到错误

  

参数化查询'（@MuscleId int，@ FitnessId nvarchar（4000））SELECT ExerciseId，Naam'期望参数'@FitnessId'未提供。

我尝试用parameter.Value = DBNull.Value修复它。但是我仍然遇到相同的错误，因为我可能做错了。

有人可以告诉我我在做什么错吗？

（{MGX.MuscleId和X.FitnessId都设置为int）

代码：

private void Exercises()
{
    string query = "SELECT ExerciseId, Naam FROM Xercises AS X " +
            "INNER JOIN MG_Exercise AS MGX ON MGX.ExerciseId = X.ExerciseId " +
            "WHERE MGX.MuscleId = @MuscleId AND X.FitnessId = @FitnessId";

    using (connection = new SqlConnection(connectionString))
    using (SqlCommand command = new SqlCommand(query, connection))
    using (SqlDataAdapter adapter = new SqlDataAdapter(command))
    {
        SqlParameter param = command.Parameters.AddWithValue("@MuscleId", comBoxMuscleGroup.SelectedValue);
        SqlParameter param2 = command.Parameters.AddWithValue("@FitnessId", comBoxTypeFitness.SelectedValue);

        if (param.Value == null)
        {
            param.Value = DBNull.Value;
        }

        if (param2.Value == null)
        {
            param2.Value = DBNull.Value;
        }

        DataTable Xdata = new DataTable();
        adapter.Fill(Xdata);    *****ERROR*****

        clbXcercises.DisplayMember = "Naam";
        clbXcercises.ValueMember = "ExerciseId";
        clbXcercises.DataSource = Xdata;
    }
}