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Hey! I ran into a little problem today... i think it's an easy one, but i don't have the answer. I have a string n declared and i want to delete all the rows in one database(sql) which contain that string(completely, not parts of the cells in the databases). so i wrote:
SqlConnection sqlconn = new SqlConnection();
sqlconn.ConnectionString = "Data Source=CATA;Initial Catalog=datagrid;Integrated Security=True;Pooling=False";
sqlconn.Open();
SqlCommand sqlcomm = new SqlCommand();
sqlcomm.CommandText = "DELETE FROM datagrid WHERE name ='"&n&"'";
sqlcomm.Connection = sqlconn;
sqlcomm.ExecuteNonQuery();
but i get the following message when i try to run the program: Error 1 Operator '&' cannot be applied to operands of type 'string' and 'string'
-- modified at 7:35 Tuesday 23rd May, 2006
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drc_no1 wrote: sqlcomm.CommandText = "DELETE FROM datagrid WHERE name ='"&n&"'";
that would be:
WHERE name ='" + n + "'";
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Yup, it works. Thanx a lot!
Now i have another problem... I have a datagrid and i have added one button column called delete. when i press delete, i want my row to disappear. But, i can't find a suitable event for clicking that button. all i find is cell content click or any other that aplies to the whole row, not only to that cell contining the row. Can u help me, pls?
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While HollyHoo's suggestion would probably work, I suggest you read this[^] article to know why your code is vulnerable to SQL injection attacks.
Regards
Senthil
_____________________________
My Blog | My Articles | WinMacro
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Hi,
I'm trying to manipulate files in a C# program, when I delete a file however I run in to problems. It seems the file isn't really deleted until my application exits. I've tried it through File.Delete() and FileInfo.Delete(), and it seems to make no difference.
The problem comes when after I have deleted the file I rescan the folder using Directory.GetFiles() and the "deleted" file is still there, except I can't read it.
Do I need to somehow flush my file deletion??
Thanks in advance.
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Hi Gubber,
did you opened the file before? Maybe there is still an open stream or somthing like this on the file. Maybe you should try to dispose the stream before?
Regards
Sebastian
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Thanks!!
That was exactly it.. I had opened a stream and forgot to Dispose of it.
Cheers!
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Hi All,
I have made a class Words.....and m using an array of it.....and i want to sort this array according to its data member Term (it also has other data members). which is a string....wat is the easiest and effeiceint way of doing it plzz tell in detail
looking forward for help
Regards,
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See this article.
You need to implement the IComparable interface and add a function CompareTo to your class.
regards
modified 12-Sep-18 21:01pm.
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Hi Sir,
Well the article u have suggested is quite complex coz i think it is about sorting objects of different classes.....i just need to sort object of a single class on the base of a specific data member........isnt there any easy way to do this 
Looking forward for help
Regards,
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You should also have read his second sentence. Here a little example:
public class MyClass : IComparable {
private string _myValue;
public int CompareTo(object o) {
return _myValue.CompareTo(((MyClass)o)._myValue);
}
}
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how can i call this in my class? and wat is the purpose of this _myValue variable.
looking forward for help
Regards,
-- modified at 11:59 Tuesday 23rd May, 2006
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Ok some more details  :
MyClass is the class you want to get sorted.
_myValue is the field or whatever by which you want to sort the data. Instead of using a field you could also use a property or something else.
Now assuming you have filled instances of this class into an ArrayList you can sort it with:
list.Sort();
If you have an array (MyClass[] myArray) of your object than you can sort it with:
Array.Sort(myArray);
Internally the Sort methods will call CompareTo to determine the correct ordering.
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Hi Sir,
i am trying to do this in this way
public class TextMiner : System.Windows.Forms.Form , IComparable
{
public Terminology[] word = new Terminology[WORDS];
private string strValue = "term";
public int CompareTo(object obj)
{
Terminology w = (Terminology) obj;
return( strValue.CompareTo( w.term ));
}
public void Indexer()
{
Aray.Sort(word);
}
}
it compiles without any error but it throws this exception during execution
An unhandled exception of type 'System.InvalidOperationException' occurred in mscorlib.dll
Additional information: Specified IComparer threw an exception.
tell me what i m doing wrong and how i can correct it....
looking forward for help
Regards,
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As you sort a Terminology array also the Terminology class should implement IComparable and not the Form.
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sir it also didnt work  i ve written the same code in the CompareTo function which i ve written in TextMiner class but it made no difference again same exception
is there any way out of this ??
looking forward for help
Regards,
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I assume some error is thrown within your CompareTo method. You should probably check if the are null values within your array or probably if sometimes term is null.
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well the exception doesnt come during sorting it comes after the sorting the statement i m cofused about is the use of
private string strValue = "term";
isnt there any error in this statement?? i mean term is the variable of terminology class and i m declaring it as a string value in TextMiner class how will this work??
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Could you please post the important part of the Terminology class and the Sort call you are currently doing? Maybe I can help you then.
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public class Terminology : IComparable
{
private string term;
private int df;
private int qTf;
private double qWeight;
private ArrayList tf = new ArrayList();
private ArrayList position= new ArrayList();
private ArrayList docID= new ArrayList();
private static int Count;
public int CompareTo(object obj)
{
Terminology w = (Terminology) obj;
return( w.term.CompareTo( w.term ));
}
public void incDF()
{
df++;
}
}
now moving to TextMiner class
public class TextMiner : System.Windows.Forms.Form , IComparable
{
const int WORDS = 20000;
public Terminology[] word = new Terminology[WORDS];
public void Indexer()
{
Array.Sort(word);
}
private string strValue = "term";
public int CompareTo(object obj)
{
Terminology w = (Terminology) obj;
return( strValue.CompareTo( w.term ));
}
}
it gives this exception
An unhandled exception of type 'System.NullReferenceException' occurred in 2ndAssignment.exe
Additional information: Object reference not set to an instance of an object.
and on this statement
for(int j = 0; j < Terminology.count-1; j++)
{
sw.Write(j+1 +"\t"+word[j].term.PadRight(20,' '));
}
and the exceptions comes when the value of j is 0....m really confused
looking forward for help
Regards,
-- modified at 5:43 Wednesday 24th May, 2006
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Several things:
1. In the first snippet the CompareTo should look like the following:
public int CompareTo(object obj)
{
Terminology w = (Terminology) obj;
return( this.term.CompareTo( w.term ));
}
In your implementation you compared w.term with itself.
2. The following part isn't needed (as far as I can see from your snippets):
private string strValue = "term";
public int CompareTo(object obj)
{
Terminology w = (Terminology) obj;
return( strValue.CompareTo( w.term ));
}
}
3. If you are getting such an error when j is 0 than my previous assumption that there are null values in your array seems right. The first element of the word array seems to be null.
You could verify this for example with the following code:
for(int j = 0; j < Terminology.count-1; j++)
{
if (word[j] == null)
MessageBox.Show("word array at index " + j + " is null");
else if (word[j].term == null)
MessageBox.Show("term property in word array at index " + j + " is null");
sw.Write(j+1 +"\t"+word[j].term.PadRight(20,' '));
}
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Robert Rohde wrote: if (word[j] == null) MessageBox.Show("word array at index " + j + " is null");
Sir it is showing entire array of word as null.....but it works perfectly fine without sorting..........how can all the values changed to null??
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using System;
using System.Collections;
namespace Test {
public class Word {
private string value;
private string anothervalue;
public string Value {
get { return value; }
set { value = value; }
}
public string AnotherValue {
get { return anothervalue; }
set { anothervalue = value; }
}
}
public class WordComparer : IComparer {
public int Compare(object x, object y) {
Word w1 = x as Word;
Word w2 = y as Word;
if (w1 == null || w2 == null) { return 0; }
return w1.Value.CompareTo(w2.Word);
}
}
public class Application {
public Word[] Sort(Word[] words) {
return Array.Sort(words, new WordComparer());
}
}
}
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Hi Sir,
when i am trying to do this in this way
public class WordComparer : IComparer
{
public int Compare(object x, object y)
{
Terminology w1 = x as Terminology;
Terminology w2 = y as Terminology;
if (w1 == null || w2 == null) { return 0; }
return w1.term.CompareTo(w2.term);
}
}
public class TextMiner : System.Windows.Forms.Form
{
some code here........
public Terminology[] word = new Terminology[WORDS];
public void Indexer()
{
Array.Sort(word, new WordComparer());
}
}
well it compiles fine but when i try to access the objects of that sorted class it gives null object reference exception
for(int i = 0; i < Terminology.Count; i ++)
{
do something with word[i];
}
well this exception comes when the value of i is 0......and the program was working perfectly fine b4 that.....
Looking forward for help
Regards,
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