使用asp.net从SQL数据库检索二进制数据

Question

I want to retrieve Binary Data from SQL Database with asp.net .but the data that is shown in the output does not match with the data that i have inserted. this is my code:

string EQuery = "SELECT * FROM Ph_Tbl_Contacts WHERE (Contact_ID =" + Contact_ID + ")";

DataSet DSs = new DataSet();
DataTable dt = new DataTable();
DataRow dr = dt.NewRow();

DSs = DB.ExecuteQueryData(EQuery);
dt = DSs.Tables[0];

// dr = dt.NewRow();
dr = dt.Rows[0];
byte[] pic;
byte[] raw = (byte[])dr["Contact_CardImage"];
//  Session[OpenDialog.STORED_IMAGE] = raw ;

and this is insert part:

byte[] IMAGEbYTE ;
IMAGEbYTE = (byte[])(Session["SessionImage"]);
string Query = "INSERT INTO Ph_Tbl_Contacts (Contact_Name, Contact_LName, " + 
               "Contact_Company, Contact_Email, Contact_Tel, " + 
               "Contact_Mobile,Contact_CardImage,Is_Public,User_ID,Save_Date)" + 
               "VALUES (N'" + Txt_Name.Text + "', N'" + Txt_LastName.Text + "', N'" + 
               Txt_CompanyName.Text + "', N'" + Txt_Mail.Text + "', N'" + 
               Txt_Telephone.Text + "', N'" + Txt_Mobile.Text + "','" + 
               IMAGEbYTE + "','" + CheckValue + "'," + 
               Session["User_ID"] + ", N'" + DateStr + "')";

DB.ExecuteQueryNoData(Query) ; 

Answer 1

Alright, let's start with cleaning your code. The first thing is to fix your INSERT code, because right now it is vulnerable to SQL injection. You need to use parametrized queries:

using (var conn = new SqlConnection("Your ConnectionString comes here"))
using (var cmd = conn.CreateCommand())
{
    conn.Open();
    cmd.CommandText =
    @"INSERT INTO Ph_Tbl_Contacts 
          (Contact_Name, 
           Contact_LName, 
           Contact_Company, 
           Contact_Email, 
           Contact_Tel, 
           Contact_Mobile, 
           Contact_CardImage, 
           Is_Public, 
           User_ID, 
           Save_Date)
      VALUES 
          (@Contact_Name, 
           @Contact_LName, 
           @Contact_Company, 
           @Contact_Email, 
           @Contact_Tel, 
           @Contact_Mobile, 
           @Contact_CardImage, 
           @Is_Public, 
           @User_ID, 
           @Save_Date)
    ";
    cmd.Parameters.AddWithValue("@Contact_Name", Txt_Name.Text);
    cmd.Parameters.AddWithValue("@Contact_LName", Txt_LastName.Text);
    cmd.Parameters.AddWithValue("@Contact_Company", Txt_CompanyName.Text);
    cmd.Parameters.AddWithValue("@Contact_Email", Txt_Mail.Text);
    cmd.Parameters.AddWithValue("@Contact_Tel", Txt_Telephone.Text);
    cmd.Parameters.AddWithValue("@Contact_Mobile", Txt_Mobile.Text);
    cmd.Parameters.AddWithValue("@Contact_CardImage", IMAGEbYTE);
    cmd.Parameters.AddWithValue("@Is_Public", CheckValue);
    cmd.Parameters.AddWithValue("@User_ID", Session["User_ID"]);
    cmd.Parameters.AddWithValue("@Save_Date", DateStr); 
    cmd.ExecuteNonQuery();
}

Here's it's worth mentioning that if the Save_Date column in your database is a datetime you should pass an instance of DateTime for the parameter and not be attempting to convert it to string => DateStr must be a DateTime.

Alright, now that you have correctly inserted the record into the database you could read it:

using (var conn = new SqlConnection("Your ConnectionString comes here"))
using (var cmd = conn.CreateCommand())
{
    conn.Open();
    cmd.CommandText = 
    @"SELECT
          Contact_CardImage
      FROM 
          Ph_Tbl_Contacts 
      WHERE 
          Contact_ID = @Contact_ID
    ";
    cmd.Parameters.AddWithValue("@Contact_ID", Txt_Name.Text); 
    using (var reader = cmd.ExecuteReader())
    {
        if (reader.Read())
        {
            byte[] raw = (byte[])reader.Items["Contact_CardImage"];
            // TODO: do something with the raw data
        }
    }
}