how elements which is in listbox can be deleted on selecting particular item of listbox

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.NET3.5

I am making desktop application using C#.NET and SQL SERVER 2008.i have taken a listbox in a form containing elements which is fetched from database.Now i want that on selecting the item which is present in the listbox should get delete I have taken a delete button
i have listbox name listbox1 containing items and btndelete to delete
below is the coding that i have tried

private void btndeleteresources_Click(object sender, EventArgs e)
      {
          SqlDataAdapter adp = new SqlDataAdapter("delete  from  Resources_Required  where Resources='"+listBox1.SelectedIndex+"'", "Data Source=SW-PC-20;Initial Catalog=PSM;Integrated Security=True");
          DataSet ds = new DataSet();
          adp.Fill(ds, "Resources_Required");
          listBox1.DataSource = ds.Tables[0];
          listBox1.DisplayMember = "Resources";
          listBox1.ValueMember = "Resources";
          cboresources.Focus();
      }

Posted 3-May-11 21:00pm

shivani 2013

Updated 3-May-11 21:07pm

v2

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Sergey Alexandrovich Kryukov 4-May-11 3:02am

Tag it! Forms, WPF, what?!
--SA

2 solutions

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Ankit Rajput · Answer 1 · 2011-05-03T21:12:00

Solution 1

Hi,

Use this

Here "conn" is your connection

C#

private void btndeleteresources_Click(object sender, EventArgs e)
      {
          SqlCommand cmd = new SqlCommand("delete  from  Resources_Required  where Resources='"+listBox1.SelectedItems[0].ToString() +"'", conn);
          cmd.ExecuteNonQuery();
          SqlDataAdapter adp = new SqlDataAdapter("Select * from  Resources_Required","Data Source=SW-PC-20;Initial Catalog=PSM;Integrated Security=True" );
          DataSet ds = new DataSet();
          adp.Fill(ds, "Resources_Required");
          listBox1.DataSource = ds.Tables[0];
          listBox1.DisplayMember = "Resources";
          listBox1.ValueMember = "Resources";
          cboresources.Focus();
      }

Try it.

Regards
AR

Posted 3-May-11 21:12pm

Ankit Rajput

Updated 4-May-11 1:11am

v4

Comments

shivani 2013 4-May-11 3:21am

no its not working....getting an error "listBox1.SelectedItems[0] does not contain definition of .Text"

Ankit Rajput 4-May-11 3:36am

Sorry. Use
listBox1.SelectedItems[0].ToString();

shivani 2013 4-May-11 5:10am

i have even tried before u wote..and this time i am getting an error
cannot find table[0]

Ankit Rajput 4-May-11 6:28am

I have updated my answer try it.

shivani 2013 4-May-11 7:05am

its not working I mean i am not getting any error while running but not deleting the elements too......and one more thing its listBox1.SelectedItems[0] not listBox1.SelectedItem[0] as it is giving error "cannt apply indexing with[] to an expression of type 'object' "

Ankit Rajput 4-May-11 7:08am

Then you have to check the query in debug mode.

shivani 2013 4-May-11 7:18am

i have checked

shivani 2013 4-May-11 7:18am

but no error

Ankit Rajput 4-May-11 7:28am

Check the Condition in your query.

shivani 2013 4-May-11 7:39am

i have checked sir..no problem in query

Ankit Rajput 4-May-11 7:43am

Do one thing Copy this query from debug mode.
And run it directly to Sql Server Query Analyzer.
Is it able to delete the data from here?

shivani 2013 4-May-11 7:55am

can u tell how
m mean where is Sql Server Query Analyzer

Ankit Rajput 4-May-11 8:03am

Which version of SQL Server do you have?

shivani 2013 4-May-11 8:06am

2008

Ankit Rajput 4-May-11 8:08am

Then open new query window.
Select the approriate database.
Type your query here and run it.
If it is able to delete the data then it will delete from code as well.

shivani 2013 4-May-11 8:27am

achaa! isko kehte hai...ok
udhar toh query run ho gai there i need to specify
delete from PSM.dbo.Resources_Required where Resources="Team";(i have to specify the value which is present in field resources)

Ankit Rajput 4-May-11 8:29am

If you dont have any matching data in the table.
Then how can you expect from a query to delete it?

shivani 2013 4-May-11 8:40am

sir i am deleting it from database then how could i write the query
delete from Resources_Required where Resources='"+listBox1.SelectedItems[0].ToString()

shivani 2013 5-May-11 3:22am

please rectify me if i am wrong anywhere

Tarun.K.S · Answer 2 · 2011-05-03T22:05:00

Solution 2

I'm not sure this code will delete or not.

Try this,

C#

string selCmdString = "SELECT *FROM Resources_Required";
SqlCommand selCommand = new SqlCommand(selCmdString, conn);

string delCmdString = "DELETE FROM Resources_Required WHERE Resources=@Res";
SqlCommand delCommand = new SqlCommand(delCmdString, conn);

SqlDataAdapter adp = new SqlDataAdapter(selCommand);
adp.DeleteCommand = delCommand;

//Adding one more thing, try this
DataRowView curRowView = (DataRowView)listBox1.SelectedItem;
String resources = curRowView["Resources"].ToString();  // Will return the current value in selected row of Column Resources

//Use SqlParameters to avoid SQL injections. Keep it as practice.
SqlParameter param = New SqlParameter();
param.ParameterName = "@Res";
//param.Value = listBox1.SelectedItem.ToString();
param.Value = resources;
param.SqlDbType = SqlDbType.SmallInt;
delCommand.Parameters.Add(param);

DataSet ds = new DataSet();
adp.Fill(ds,"Resources_Required");

DataTable dt = ds.Tables["Resources_Required"];
foreach (DataRow ro in dt.Rows) 
   {
    if (ro["Resources"].ToString() == resources) 
    {
        ro.Delete();
        break;
    }
   }
adp.Update(ds,"Resources_Required");
listBox1.DataSource = ds.Tables[0];
listBox1.DisplayMember = "Resources";
listBox1.ValueMember = "Resources";
cboresources.Focus();

Try now.

Posted 3-May-11 22:05pm

Tarun.K.S

Updated 4-May-11 1:54am

v6

Comments

shivani 2013 4-May-11 5:17am

neah not working
no item was deleted

Tarun.K.S 4-May-11 6:36am

I have updated the answer. Check now.

shivani 2013 4-May-11 7:16am

getting error
instead of Tables() its Table[] in DataTable dt = ds.Tables("Resources_Required");
and warning
if (ro["Resources"] == listBox1.SelectedItem.ToString())
"Possible unintended reference comparison,to get a value comparison,cast the left hand side to type'string'

Tarun.K.S 4-May-11 7:23am

Updated. You can check now.

shivani 2013 4-May-11 7:33am

it doesnt contain any definition for .item in
if (ro.Item["Resources"] == listBox1.SelectedItem.ToString())
and one more thing
its SqlParameter param = new SqlParameter();
instead of
SqlParameter param = New SqlParameter;

Tarun.K.S 4-May-11 7:41am

Updated now. In VB.NET .Item was present but not in C#. Thanks for letting me know that. It should work now.

shivani 2013 4-May-11 7:45am

warning
if (ro["Resources"] == listBox1.SelectedItem.ToString())
"Possible unintended reference comparison,to get a value comparison,cast the left hand side to type'string'
and nothing happened i mean not deleting the element

Tarun.K.S 4-May-11 7:55am

Ohkay buddy, I have updated it again. Check now! :D

shivani 2013 4-May-11 7:59am

getting an error"Failed to convert parameter value from a string to a Int16

Tarun.K.S 4-May-11 8:05am

Damn it. What is your dataType for column Resources? if its int, then remove the ToString and write int resources = (int)curRowView["Resources"];

shivani 2013 4-May-11 23:54pm

its string only

shivani 2013 5-May-11 3:22am

Sir its dtring onlt

shivani 2013 5-May-11 3:23am

Sir its string only