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How do reload data from database
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C#
I am making a web application that have student's record and test papers. I want to reload the data from database if computer will be off suddenly(may be due to light issue or laptop battery issue) while student is doing his/her test. All marked answer should be display again when computer turn on again. I can't understand how to do it. Below is my code.
Can anyone tell me what to do.

What I have tried:

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.Sql;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page
{

SqlConnection Con;
SqlCommand Cmd;
SqlDataAdapter da;
SqlDataReader dr;
DataSet ds;
DataTable dt = new DataTable();
int recordcount = 0;
int i = 0;
// string strConnString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
protected void Page_Load(object sender, EventArgs e)
{

Con = new SqlConnection("Data Source=DESKTOP-Q69PRF4;Initial Catalog=new;Integrated Security=True");
Cmd = new SqlCommand("SELECT * FROM student where category='"+Session["test"]+ "'", Con);
da = new SqlDataAdapter(Cmd);
ds = new DataSet("student");

Con.Open();
this.da.Fill(ds, "student");
Cmd = new SqlCommand("select * from student where Question='" + TextBox1.Text + "'", Con);
dr = Cmd.ExecuteReader();
while(dr.Read())
{
Label7.Text = dr["Q_ID"].ToString();
lblmarks.Text = dr["TotalMarks"].ToString();

}


recordcount = ds.Tables[0].Rows.Count;
Response.Write("Record Count : " + recordcount);


if (recordcount > i)
{
TextBox1.Text = ds.Tables[0].Rows[i]["Question"].ToString();
Label2.Text = ds.Tables[0].Rows[i]["Choice1"].ToString();
Label3.Text = ds.Tables[0].Rows[i]["Choice2"].ToString();
Label4.Text = ds.Tables[0].Rows[i]["Choice3"].ToString();
Label5.Text = ds.Tables[0].Rows[i]["Choice4"].ToString();
Label6.Text = ds.Tables[0].Rows[i]["Choice5"].ToString();
}
else
{
Response.Write("There are no records in this category");
}
if (i == 0)
{
RadioButton1.Visible = true;
RadioButton2.Visible = true;
RadioButton3.Visible = true;
RadioButton4.Visible = true;
RadioButton5.Visible = true;
CheckBox1.Visible = false;
CheckBox2.Visible = false;
CheckBox3.Visible = false;
CheckBox4.Visible = false;
CheckBox5.Visible = false;

}
dr.Read();


Con.Close();

}


protected void Button2_Click(object sender, EventArgs e)
{

//Con.Open();
//Cmd = new SqlCommand("select * from student where Question='" + TextBox1.Text + "'", Con);
//dr = Cmd.ExecuteReader();
//while (dr.Read())
//{
// Label7.Text = dr["Q_ID"].ToString();
//}
//Con.Close();

TextBox2.Text = (int.Parse(TextBox2.Text) + 1).ToString();

i = Convert.ToInt32(TextBox2.Text);


TextBox1.Text = ds.Tables[0].Rows[i]["Question"].ToString();
Label2.Text = ds.Tables[0].Rows[i]["Choice1"].ToString();
Label3.Text = ds.Tables[0].Rows[i]["Choice2"].ToString();
Label4.Text = ds.Tables[0].Rows[i]["Choice3"].ToString();
Label5.Text = ds.Tables[0].Rows[i]["Choice4"].ToString();
Label6.Text = ds.Tables[0].Rows[i]["Choice5"].ToString();


if (i == 1)
{
RadioButton1.Visible = false;
RadioButton2.Visible = false;
RadioButton3.Visible = false;
RadioButton4.Visible = false;
RadioButton5.Visible = false;
CheckBox1.Visible = true;
CheckBox2.Visible = true;
CheckBox3.Visible = true;
CheckBox4.Visible = true;
CheckBox5.Visible = true;

}

else if (i == 2)
{
RadioButton1.Visible = true;
RadioButton2.Visible = true;
RadioButton3.Visible = true;
RadioButton4.Visible = true;
RadioButton5.Visible = true;
CheckBox1.Visible = false;
CheckBox2.Visible = false;
CheckBox3.Visible = false;
CheckBox4.Visible = false;
CheckBox5.Visible = false;

}
else if (i == 3)
{
RadioButton1.Visible = false;
RadioButton2.Visible = false;
RadioButton3.Visible = false;
RadioButton4.Visible = false;
RadioButton5.Visible = false;
CheckBox1.Visible = true;
CheckBox2.Visible = true;
CheckBox3.Visible = true;
CheckBox4.Visible = true;
CheckBox5.Visible = true;

}
else
{
RadioButton1.Visible = true;
RadioButton2.Visible = true;
RadioButton3.Visible = true;
RadioButton4.Visible = true;
RadioButton5.Visible = true;
CheckBox1.Visible = false;
CheckBox2.Visible = false;
CheckBox3.Visible = false;
CheckBox4.Visible = false;
CheckBox5.Visible = false;


}

}



protected void previous_Click(object sender, EventArgs e)
{
//Con.Open();
//Cmd = new SqlCommand("select * from student where Question='" + TextBox1.Text + "'", Con);
//dr = Cmd.ExecuteReader();
//while (dr.Read())
//{
// Label7.Text = dr["Q_ID"].ToString();
//}
//Con.Close();
TextBox2.Text = (int.Parse(TextBox2.Text) - 1).ToString();
i = Convert.ToInt32(TextBox2.Text);

// Label7.Text = ds.Tables[0].Rows[i]["Q_ID"].ToString();

TextBox1.Text = ds.Tables[0].Rows[i]["Question"].ToString();
Label2.Text = ds.Tables[0].Rows[i]["Choice1"].ToString();
Label3.Text = ds.Tables[0].Rows[i]["Choice2"].ToString();
Label4.Text = ds.Tables[0].Rows[i]["Choice3"].ToString();
Label5.Text = ds.Tables[0].Rows[i]["Choice4"].ToString();
Label6.Text = ds.Tables[0].Rows[i]["Choice5"].ToString();



if (i == 1)
{
RadioButton1.Visible = false;
RadioButton2.Visible = false;
RadioButton3.Visible = false;
RadioButton4.Visible = false;
RadioButton5.Visible = false;
CheckBox1.Visible = true;
CheckBox2.Visible = true;
CheckBox3.Visible = true;
CheckBox4.Visible = true;
CheckBox5.Visible = true;

}
else if (i == 2)
{
RadioButton1.Visible = true;
RadioButton2.Visible = true;
RadioButton3.Visible = true;
RadioButton4.Visible = true;
RadioButton5.Visible = true;
CheckBox1.Visible = false;
CheckBox2.Visible = false;
CheckBox3.Visible = false;
CheckBox4.Visible = false;
CheckBox5.Visible = false;

}
else if (i == 3)
{
RadioButton1.Visible = false;
RadioButton2.Visible = false;
RadioButton3.Visible = false;
RadioButton4.Visible = false;
RadioButton5.Visible = false;
CheckBox1.Visible = true;
CheckBox2.Visible = true;
CheckBox3.Visible = true;
CheckBox4.Visible = true;
CheckBox5.Visible = true;
}
else
{
RadioButton1.Visible = true;
RadioButton2.Visible = true;
RadioButton3.Visible = true;
RadioButton4.Visible = true;
RadioButton5.Visible = true;
CheckBox1.Visible = false;
CheckBox2.Visible = false;
CheckBox3.Visible = false;
CheckBox4.Visible = false;
CheckBox5.Visible = false;
}


}

protected void Submit_Click(object sender, EventArgs e)
{



string cs = "Data Source=DESKTOP-Q69PRF4;Initial Catalog=new;Integrated Security=True";
SqlConnection con = new SqlConnection(cs);
if (con.State == ConnectionState.Open)
{
con.Close();
}
//con.Open();
//Cmd = new SqlCommand("select * from student where Question='" + TextBox1.Text + "'", con);
//SqlDataReader r = Cmd.ExecuteReader();
////SqlDatareader dr = Cmd.ExecuteReader();
//while (r.Read())
//{
// Label7.Text = r["Q_ID"].ToString();
//}
//con.Close();
con.Open();

if (RadioButton1.Visible == true)
{
if (RadioButton1.Checked)
{
string query = "insert into CBE(Q_ID,StID,Answer)values('" + Label7.Text + "','" + Session["new"] + "','" + lblA.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (RadioButton2.Checked )
{
string query = "insert into CBE(Q_ID,StID,Answer)values('" + Label7.Text + "','" + Session["new"] + "','" + lblB.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (RadioButton3.Checked )
{
string query = "insert into CBE(Q_ID,StID,Answer)values('" + Label7.Text + "','" + Session["new"] + "','" + lblC.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (RadioButton4.Checked )
{
string query = "insert into CBE(Q_ID,StID,Answer)values('" + Label7.Text + "','" + Session["new"] + "','" + lblD.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (RadioButton5.Checked )
{
string query = "insert into CBE(Q_ID,StID,Answer)values('" + Label7.Text + "','" + Session["new"] + "','" + lblE.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else
{
if (CheckBox1.Checked)
{
string query = "insert into CBE(Q_ID,StID,Ans1)values('" + Label7.Text + "','" + Session["new"] + "','" + lblA.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (CheckBox2.Checked)
{
string query = "insert into CBE(Q_ID,StID,Ans2)values('" + Label7.Text + "','" + Session["new"] + "','" + lblB.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (CheckBox3.Checked)
{
string query = "insert into CBE(Q_ID,StID,Ans3)values('" + Label7.Text + "','" + Session["new"] + "','" + lblC.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (CheckBox4.Checked)
{
string query = "insert into CBE(Q_ID,StID,Ans4)values('" + Label7.Text + "','" + Session["new"] + "','" + lblD.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
else if (CheckBox5.Checked)
{
string query = "insert into CBE(Q_ID,StID,Ans5)values('" + Label7.Text + "','" + Session["new"] + "','" + lblE.Text + "')";
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();

}
}
}
con.Close();

con.Open();
Cmd = new SqlCommand("select Solution from Student where Q_Id='"+Label7.Text+"'",con);
SqlDataReader dr = Cmd.ExecuteReader();
while(dr.Read())
{
Label8.Text = dr["Solution"].ToString();

}
con.Close();
//con.Open();
//string qr = "Update CBE Set Answer='" + Label8.Text + "'where Q_ID='"+Label7.Text+"'";

//Cmd = new SqlCommand(qr,con);

//dr = Cmd.ExecuteReader();

//while (dr.Read())
//{
// lblans.Text = dr["Answer"].ToString();
//}
//con.Close();
con.Open();
Cmd = new SqlCommand("select * from CBE where Q_ID='" + Label7.Text + "'", con);

dr = Cmd.ExecuteReader();

while (dr.Read())
{
if (RadioButton1.Visible == true)
{
if (RadioButton1.Checked)
{
lblcheck.Text = dr["Answer"].ToString();
}
else if (RadioButton2.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else if (RadioButton3.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else if (RadioButton4.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else if (RadioButton5.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else
{
lblcheck.Text = "";
}
}
else
{
if (CheckBox1.Checked)
{
lblcheck.Text = dr["Answer"].ToString();
}
else if (CheckBox2.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else if (CheckBox3.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else if (CheckBox4.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else if (CheckBox5.Checked)
{
lblcheck.Text = dr["Answer"].ToString();

}
else
{
lblcheck.Text = "";
}
}

}
con.Close();
con.Open();
Cmd = new SqlCommand("Select TotalMarks from Student where Q_ID='" + Label7.Text + "'", con);
dr = Cmd.ExecuteReader();
while(dr.Read())
{
lblques.Text = dr["TotalMarks"].ToString();
}
con.Close();
con.Open();
if (lblcheck.Text == Label8.Text)
{

Cmd = new SqlCommand("Update CBE Set StMarks='" + lblques.Text + "'where Q_ID='" + Label7.Text + "'", con);

}
else if (lblcheck.Text != Label8.Text)
{
Cmd = new SqlCommand("Update CBE Set StMarks='" + lblm.Text + "'where Q_ID='" + Label7.Text + "'", con);

}
else
lblques.Text = "Please Select at least one option";
Cmd.ExecuteNonQuery();

con.Close();


}


void clear()

{

RadioButton1.Checked = false;
RadioButton2.Checked = false;
RadioButton3.Checked = false;
RadioButton4.Checked = false;
RadioButton5.Checked = false;
CheckBox1.Checked = false;
CheckBox2.Checked = false;
CheckBox3.Checked = false;
CheckBox4.Checked = false;
CheckBox5.Checked = false;
}




}
Posted
Updated 27-Sep-17 22:14pm
Add a Solution

1 solution

You have bigger problems that you think - and just dumping all your code on us and expecting us to sort out what the heck you mean is not that - it's just rude.

Ignore the problem you have at the moment, and fix this first:
Never concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead.

When you concatenate strings, you cause problems because SQL receives commands like:
SQL
SELECT * FROM MyTable WHERE StreetAddress = 'Baker's Wood'
The quote the user added terminates the string as far as SQL is concerned and you get problems. But it could be worse. If I come along and type this instead: "x';DROP TABLE MyTable;--" Then SQL receives a very different command:
SQL
SELECT * FROM MyTable WHERE StreetAddress = 'x';DROP TABLE MyTable;--'
Which SQL sees as three separate commands:
SQL
SELECT * FROM MyTable WHERE StreetAddress = 'x';
A perfectly valid SELECT
SQL
DROP TABLE MyTable;
A perfectly valid "delete the table" command
SQL
--'
And everything else is a comment.
So it does: selects any matching rows, deletes the table from the DB, and ignores anything else.

So ALWAYS use parameterized queries! Or be prepared to restore your DB from backup frequently. You do take backups regularly, don't you?
 
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Posted
Comments
Member 13361792 28-Sep-17 5:10am    
I am taking backup. And thanks for your advice.
Add a Solution

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