Develop Reference

Update Sql with gridview checkbox

I have a gridview set in ASP.Net that has a name and a checkbox.
<h4>Current Instructor</h4>
<div class="hide-overflow">
<asp:GridView runat="server" ID="GridViewInstructor" DataSourceID="SqlDataSourceInstructor" AutoGenerateColumns="false" CssClass="table table-bordered table-striped" ShowHeader="false" EmptyDataText="No Instructor associated to class." DataKeyNames="Instructor">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:CheckBox ID="CBInstructorPrimary" runat="server" Checked='<%#Eval("Primary")%>' OnCheckedChanged="PrimaryUpdate" AutoPostBack="true" />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="InstructorName" />
</Columns>
</asp:GridView>
<asp:SqlDataSource runat="server" ID="SqlDataSourceInstructor" DataSourceMode="DataReader" ConnectionString="<%$ ConnectionStrings:HRAgriConnectionString %>"
SelectCommand="
SELECT a.Primary, a.ClassID, a.Instructor, b.LName + ', ' + b.FName as InstructorName
FROM tblClass a
LEFT JOIN tblUser b
ON a.Instructor = b.UserName
WHERE a.ClassID = #classID
ORDER BY a.Primary DESC">
<SelectParameters>
<asp:QueryStringParameter Name="classID" QueryStringField="cid" Type="String" />
</SelectParameters>
</asp:SqlDataSource>
</div>
This makes a gridview table that looks like
my c# code behind looks like this
protected void PrimaryUpdate(object sender, EventArgs e)
{
//CheckBox activeCheckBox = sender as CheckBox;
//foreach (GridViewRow rw in GridViewInstructor.Rows)
//{
// CheckBox chkBx = (CheckBox)rw.FindControl("CBInstructorPrimary");
// if (chkBx != activeCheckBox)
// {
// chkBx.Checked = false;
// }
// else
// {
// chkBx.Checked = true;
// }
//}
string constr = ConfigurationManager.ConnectionStrings["ConString"].ConnectionString;
using (SqlConnection con = new SqlConnection(constr))
{
using (SqlCommand cmd = new SqlCommand())
{
cmd.CommandText = "UPDATE tblClass SET [Primary] = #Primary WHERE classID=#classID and Instructor = #InstructorName";
cmd.Connection = con;
con.Open();
foreach (GridViewRow row in GridViewInstructor.Rows)
{
//Get Instructor Name.
string InstructorName = row.Cells[0].Text;
//Get the Class Id from the DataKey property.
classID = Request.QueryString["cid"];
//Get the checked value of the CheckBox.
bool Primary = (row.FindControl("CBInstructorPrimary") as CheckBox).Checked;
//Save to database
cmd.Parameters.Clear();
cmd.Parameters.AddWithValue("#InstructorName", InstructorName);
cmd.Parameters.AddWithValue("#classID", classID);
cmd.Parameters.AddWithValue("#Primary", Primary);
cmd.ExecuteNonQuery();
}
con.Close();
Response.Redirect(Request.Url.AbsoluteUri);
}
}
}
The outcome should be if you check another checkbox it will update the Primary field (which is a bit field) to 1 if checked and all others in that group will be set to 0. And only 1 checkbox can be checked at a time. I know I have commented out the top part for now. I just haven't been able to figure out how to get this working.

Object reference not set to an instance of an object. want to select all columns of the row button clicked on gridview

All I want to do is when A user clicks on "See more" button on gridview, He will get all the columns of the row button clicked on detailView1.. But I dont know where Im going wrong. Im working on C# asp.net
Can anyone help? Thanks in advance.
protected void Page_Load(object sender, EventArgs e)
{
var conString = ConfigurationManager.ConnectionStrings["CONSTRING"].ConnectionString;
SqlConnection con = new SqlConnection(conString);
DetailsView1.Visible = false;
SqlCommand cmd1 = new SqlCommand("SELECT cars.carid, cars.make, cars.model, cars.condition, cars.amount, img.img FROM cars INNER JOIN img ON cars.carid = img.carid ", con);
SqlDataAdapter sda1 = new SqlDataAdapter(cmd1);
DataTable dt = new DataTable();
sda1.Fill(dt);
GridView1.DataSource = dt;
GridView1.DataBind();
}
protected void Button2_Clicked(object sender, EventArgs e)
{
var conString = ConfigurationManager.ConnectionStrings["CONSTRING"].ConnectionString;
SqlConnection con = new SqlConnection(conString);
foreach (GridViewRow row in this.GridView1.Rows)
{
Label lblshow = (Label)GridView1.Rows[row.RowIndex].FindControl("carid");
SqlCommand cmd1 = new SqlCommand("Select * from cars where carid='" + lblshow.Text + "'", con);
SqlDataAdapter sda1 = new SqlDataAdapter(cmd1);
DataTable dt = new DataTable();
sda1.Fill(dt);
DetailsView1.DataSource = dt;
DetailsView1.DataBind();
}
}
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="True" Width="1000px" AllowPaging="True" PageSize="8" CssClass="Grid" AlternatingRowStyle-CssClass="alt" PagerStyle-CssClass="pgr">
<AlternatingRowStyle CssClass="alt"></AlternatingRowStyle><PagerStyle CssClass="pgr"></PagerStyle>
<Columns>
<asp:TemplateField>
<HeaderTemplate>Select</HeaderTemplate>
<ItemTemplate>
<asp:Button runat="server" Text="See more" OnClick="Button2_Clicked" />
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<HeaderTemplate>Image</HeaderTemplate>
<ItemTemplate>
<img src='data:image/jpg;base64,<%# Eval("img") != System.DBNull.Value ? Convert.ToBase64String((byte[])Eval("img")) : string.Empty %>' alt="image" height="100" width="150"/>
</ItemTemplate>
</asp:TemplateField>
</Columns>

IsPostback on the page load event. Hope your problem get resolved.

CheckBox is not working when I am pressing the button

I am working with Asp.Net C# and want to take the id of the row with a checkbox from the GridView.
With the code above if is checked the only think i am getting with debug is:
chk: {Text = "" Checked = false}
What i am doing wrong and how i can fix this?
<!-- language: lang-css -->
protected void Page_Load(object sender, EventArgs e)
{
string query = "SELECT * FROM routedoc WHERE Recipient=#user ";
string user = Session["user"].ToString();
MySqlConnection con = new MySqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["imagingConnectionString"].ConnectionString);
MySqlCommand cmd = new MySqlCommand(query, con);
cmd.Parameters.AddWithValue("#user", user);
con.Open();
DataTable dataTable = new DataTable();
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
da.Fill(dataTable);
GridView1.DataSource = dataTable;
GridView1.DataBind();
if(!IsPostBack)
{
BindDropDown();
}
}
private void BindDropDown()
{
string user = Session["user"].ToString();
using (MySqlConnection con2 = new MySqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["imagingConnectionString"].ConnectionString))
{
MySqlDataAdapter adp = new MySqlDataAdapter("SELECT RouteNo,sender FROM routedoc WHERE Recipient = #user ", con2);
adp.SelectCommand.Parameters.AddWithValue("?user", user);
DataTable dt = new DataTable();
adp.Fill(dt);
if (dt.Rows.Count > 0)
{
DropDownList1.DataSource = dt;
DropDownList1.DataTextField = "sender";
DropDownList1.DataValueField = "RouteNo";
DropDownList1.DataBind();
}
}
}
protected void Button1_Click(object sender, EventArgs e)
{
// Response.Write(GridView1.SelectedRow.Cells[1].Text);
foreach(GridViewRow row in GridView1.Rows)
{
var chk = row.FindControl("box") as CheckBox ;
if (chk.Checked)
{
var id = row.FindControl("RouteNo") as Label;
Response.Write(id.Text);
}
}
}
routedoc.aspx:
<%# Page Language="C#" AutoEventWireup="true" CodeBehind="routedoc.aspx.cs" Inherits="WebApplication2.WebForm2" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h1>page 2<asp:DropDownList ID="DropDownList1" runat="server" Height="20px" AutoPostBack="True" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged" Width="136px" >
</asp:DropDownList>
</h1>
</div>
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Recipient,DocHandle,Sender" OnSelectedIndexChanged="GridView1_SelectedIndexChanged" >
<Columns>
<asp:BoundField DataField="RouteNo" HeaderText="RouteNo" InsertVisible="False" SortExpression="RouteNo" />
<asp:BoundField DataField="Recipient" HeaderText="Recipient" ReadOnly="True" SortExpression="Recipient" />
<asp:BoundField DataField="DocHandle" HeaderText="DocHandle" ReadOnly="True" SortExpression="DocHandle" />
<asp:BoundField DataField="Sender" HeaderText="Sender" ReadOnly="True" SortExpression="Sender" />
<asp:BoundField DataField="TermNo" HeaderText="TermNo" SortExpression="TermNo" />
<asp:BoundField DataField="SentDate" HeaderText="SentDate" SortExpression="SentDate" />
<asp:BoundField DataField="DueDate" HeaderText="DueDate" SortExpression="DueDate" />
<asp:BoundField DataField="SentTime" HeaderText="SentTime" SortExpression="SentTime" />
<asp:BoundField DataField="DueTime" HeaderText="DueTime" SortExpression="DueTime" />
<asp:BoundField DataField="Action" HeaderText="Action" SortExpression="Action" />
<asp:BoundField DataField="Notes" HeaderText="Notes" SortExpression="Notes" />
<asp:BoundField DataField="BUDate" HeaderText="BUDate" SortExpression="BUDate" />
<asp:TemplateField HeaderText="Select">
<ItemTemplate><asp:CheckBox ID="Box" runat="server"/>
</ItemTemplate></asp:TemplateField>
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:imagingConnectionString %>" ProviderName="<%$ ConnectionStrings:imagingConnectionString.ProviderName %>" SelectCommand="SELECT * FROM routedoc "></asp:SqlDataSource>
<asp:Button ID="Button1" runat="server" Height="43px" OnClick="Button1_Click" Text="DELETE" Width="109px" />
</form>
</body>
</html>

This is caused by the fact that you always bind your GridView1 with data,
even on post-back. This is causing that all check box-es remain unchecked.
Remove grid loading if you are in post-back, and it should work fine.
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
string query = "SELECT * FROM routedoc WHERE Recipient=#user ";
string user = Session["user"].ToString();
MySqlConnection con = new MySqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["imagingConnectionString"].ConnectionString);
MySqlCommand cmd = new MySqlCommand(query, con);
cmd.Parameters.AddWithValue("#user", user);
con.Open();
DataTable dataTable = new DataTable();
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
da.Fill(dataTable);
GridView1.DataSource = dataTable;
GridView1.DataBind();
BindDropDown();
}
}
If you, however, need to load grid even in post-back, I will tell you a fix for that.

Whenever you bind a data to a data control in Page_Load event, please consider using Page.IsPostBack
protected void Page_Load(object sender, EventArgs e)
{
if(!Page.IsPostBack)
{
// bind data
}
}
This is because, when you click a button, your page will be still refreshed, which means you will bind the same data to gridview again, resulting in unchecked checkboxes. You can check whether the page is loaded by a button click (Page.IsPostBack) or the page is loaded the first time (!Page.IsPostBack), and do your data binding accordingly.
Hope this makes sense!

How to use the checkboxs in gridview?

I have a asp.net form displaying the user details from an Oracle database, using a grid-view. I even managed to get a check-box field in the grid-view using the following template..
<asp:TemplateField>
<ItemTemplate>
<asp:CheckBox runat="server" ID="chck"/>
</ItemTemplate>
</asp:TemplateField>
I want the admin to be able to select multiple entries using the check-boxes and perform a certain action on them. I tried using, for the delete operation, the following
for (int i = 0; i < GridView1.Rows.Count; i++)
{
if (Convert.ToBoolean(GridView1.Rows[i].Cells[1].Value == true))
GridView1.Rows.RemoveAt[i];
}
However, this shows an error. Apparently, each check-box on each row must have its own unique index. How do I get to it?
Any sort of help will be appreciated. Thanx :)

You need to find control inside your gridview row using findControl
for (int i = 0; i < GridView1.Rows.Count; i++)
{
CheckBox cb1 = (CheckBox)GridView1.Rows[i].FindControls("chck");
if(cb1.Checked)
GridView1.Rows.RemoveAt[i];
}

Use find control to get checkboxes:
for (int i = 0; i < GridView1.Rows.Count; i++)
{
CheckBox chck = (CheckBox)GridView1.Rows[i].FindControl("chck");
if (chck != null)
{
if (chck.Checked)
{
GridView1.Rows.RemoveAt[i];
}
}
}

This is Aspx FIle :
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
BackColor="White" BorderColor="#336699" BorderStyle="Solid" BorderWidth="1px"
CellPadding="0" CellSpacing="0" DataKeyNames="CategoryID" Font-Size="10"
Font-Names="Arial" GridLines="Vertical" Width="40%">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:CheckBox ID="chkStatus" runat="server"
AutoPostBack="true" OnCheckedChanged="chkStatus_OnCheckedChanged"
Checked='<%# Convert.ToBoolean(Eval("Approved")) %>'
Text='<%# Eval("Approved").ToString().Equals("True") ? " Approved " : " Not Approved " %>' />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField="CategoryID" HeaderText="CategoryID" />
<asp:BoundField DataField="CategoryName" HeaderText="CategoryName" />
</Columns>
<HeaderStyle BackColor="#336699" ForeColor="White" Height="20" />
</asp:GridView>
This is CS File :
protected void Page_Load(object sender, EventArgs e)
{
if (!Page.IsPostBack)
{
LoadData();
}
}
private void LoadData()
{
string constr = #"Server=.\SQLEXPRESS;Database=TestDB;uid=waqas;pwd=sql;";
string query = #"SELECT CategoryID, CategoryName, Approved FROM Categories";
SqlDataAdapter da = new SqlDataAdapter(query, constr);
DataTable table = new DataTable();
da.Fill(table);
GridView1.DataSource = table;
GridView1.DataBind();
}
public void chkStatus_OnCheckedChanged(object sender, EventArgs e)
{
CheckBox chkStatus = (CheckBox)sender;
GridViewRow row = (GridViewRow)chkStatus.NamingContainer;
string cid = row.Cells[1].Text;
bool status = chkStatus.Checked;
string constr = #"Server=.\SQLEXPRESS;Database=TestDB;uid=waqas;pwd=sql;";
string query = "UPDATE Categories SET Approved = #Approved WHERE CategoryID = #CategoryID";
SqlConnection con = new SqlConnection(constr);
SqlCommand com = new SqlCommand(query, con);
com.Parameters.Add("#Approved", SqlDbType.Bit).Value = status;
com.Parameters.Add("#CategoryID", SqlDbType.Int).Value = cid;
con.Open();
com.ExecuteNonQuery();
con.Close();
LoadData();
}

How to delete a row from DB (*.mdb) in c#

I have an access DB (.mdb) named: Programs, with one table named: Data. By using the DataGridView I present the data from the table Data. I want to delete a row from the DataGridView and from the DB during runtime. Does anyone know how to do that (using C#)?
Another question I have is, who can i run queries on my DB?
thanks!

Very simple.
I suppose in your datagrid you have a check box by choosing which you will be able to choose the rows that you want to delete. And assuming you have a submit button, so after choosing the rows click on the submit button. In the button's click event call the Delete query say delete from tblname where id = #id [#id is the id that will be passed from your grid]
After that just populate the grid e.g. select * from tblname
e.g.
Aspx code
<asp:GridView runat="server" ID="gvTest" Width="100%" AutoGenerateColumns="false">
<Columns>
<asp:TemplateField HeaderText="Select" ItemStyle-HorizontalAlign="Center" ItemStyle-Width="5%">
<ItemTemplate>
<asp:CheckBox ID="chkDel" runat="server" />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField HeaderText="RegID" DataField="RegID" ItemStyle-Width="10%">
<ItemStyle HorizontalAlign="Left"/>
</asp:BoundField>
<asp:TemplateField HeaderText="Name" ItemStyle-Width="22%" ItemStyle-HorizontalAlign="Left">
<ItemTemplate>
<asp:Label ID="lblName" runat="server" Width="100%" Text= '<%# DataBinder.Eval(Container.DataItem, "UserName")%>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
<br>
<asp:Button runat="server" ID="btnSubmit" Text="Submit" OnClick="btnSubmit_Click"></asp:Button>
Submit button cilck event's code
protected void btnSubmit_Click(object sender, EventArgs e)
{
for (int count = 0; count < gvTest.Rows.Count; count++ )
{
CheckBox chkSelect = (CheckBox)gvTest.Rows[count].FindControl("chkDel");
if (chkSelect != null)
{
if (chkSelect.Checked == true)
{
//Receiveing RegID from the GridView
int RegID = Int32.Parse((gvTest.Rows[count].Cells[1].Text).ToString());
object result = DeleteRecord(RegID); //DeleteRecord Function will delete the record
}
}
}
PopulateGrid(); //PopulateGrid Function will again populate the grid
}
public void DeleteRecord(int RegId)
{
string connectionPath = "Data Source=<your data source>;Initial Catalog=<db name>;Integrated Security=True;userid='test';pwd='test'";
string command = "";
SqlConnection connection = new SqlConnection(#connectionPath);
command = "delete from tblname where id = " + RegId
try
{
connection.Open();
SqlCommand cmd = new SqlCommand(command, connection);
cmd.ExecuteNonQuery();
}
catch (SqlException sqlExcep) {}
finally
{
connection.Close();
}
}
public void PopulateGrid()
{
DataTable dt = new DataTable();
dt = GetRecord();
if(dt !=null && dt.rows.count>0)
{
gvTest.DataSource = dt;
gvTest.DataBind();
}
}
public DataTable GetRecord()
{
string connectionPath = "Data Source=<your data source>;Initial Catalog=<db name>;Integrated Security=True;userid='test';pwd='test'";
string command = "";
SqlDataAdapter adapter = new SqlDataAdapter();
SqlConnection connection = new SqlConnection(#connectionPath);
command = "Select * from tblname" ;
connection.Open();
SqlCommand sqlCom = new SqlCommand(command, connection);
adapter.SelectCommand = sqlCom;
DataTable table = new DataTable();
adapter.Fill(table);
return table;
}
Hope this makes sense.