Column count doesn't match value count at row 1

for (int x = 2; x < rowCount; x++)
        {

            string str = xlRange.Cells[x, 2].Text;

            string query = "INSERT INTO feture (F1) VALUES (" + str + ")";
            MessageBox.Show(x.ToString());
            MySqlCommand cmd = new MySqlCommand(query, conect);
            cmd.ExecuteScalar();

        }

string query = "INSERT INTO feture (F1) VALUES (" + str + ")";

string query = "INSERT INTO feture (F1) VALUES ( '" + str + "' )";

string query = "INSERT INTO feture (F1) VALUES (@value)";
MySqlCommand cmd = new MySqlCommand(query, conect);
cmd.Parameters.AddWithValue("@value", str);
cmd.ExecuteScalar();