错误：不允许从数据类型varchar到varbinary（max）的隐式转换。 使用CONVERT函数运行此查询

Question

This is my program for uploading an image:

 protected void Button1_Click(object sender, EventArgs e)
{
    string car_model = TextBox1.Text;
    string car_brand = TextBox2.Text;
    string car_type = TextBox3.Text;
    int dist_travel = int.Parse(TextBox4.Text);
    int mileage = int.Parse(TextBox5.Text);
    string car_condition = TextBox6.Text;
    string car_owner = TextBox7.Text;
    string car_color = TextBox8.Text;
    int car_price = int.Parse(TextBox9.Text);

    if (FileUpload1.HasFile)
    {
        byte[] fdata = FileUpload1.FileBytes;

        string con_string = @"data source=(local);initial catalog=Automobile;integrated security=true";
        SqlConnection con = new SqlConnection();
        con.ConnectionString = con_string;
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = con;
        cmd.CommandText = "Insert into vehicle_details values ('" + car_model + "','" + car_type + "','" + dist_travel + "','" + mileage + "','" + car_condition + "','" + car_owner + "','" + car_color + "','" + fdata + "','" + car_price + "')";
        con.Open();
        cmd.ExecuteNonQuery();
        con.Close();
    }
}

then it throws the following error:

Implicit conversion from data type varchar to varbinary(max) is not allowed. Use the CONVERT function to run this query.

And structure of database is car_model varchar, car_type varchar, dist_travel int, mileage int,car_condition varchar, car_owner varchar, car_color varchar, fdata varbinary(MAX), car_price varchar

Answer 1

You may have declared fdata as byte[] but the section of code that reads

... + "','" + fdata + "','" + ....

is forcing it into a string so that it can be part of the command text

You're going to have to parameterise the query