• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 741
  • Last Modified:

C#: how to find out if returned dataTable is empty?

Hi again...
I make a query to our database and get a result back.
I need to make the check if the something was retunred form the DB or nothing.

-------- in VB it was pretty simple: --------
set SQLresult = connection.execute("SELECT...whatever...")
if (SQLresult.EOF) then
    'error!
else
   'do a loop
end if
--------


What is the usual way to do this in C#?

Thx
0
Smoerble
Asked:
Smoerble
  • 4
  • 3
  • 2
  • +3
1 Solution
 
ptmcompCommented:
Here you can find sample code for DataReader:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconTheADONETDataReader.asp

If you have a DataTable (needs to be loaded by a Sql/OleDBDataAdapter) you can just check dataTable.Rows.Count
0
 
ShrirajCommented:
You can use try, catch method.

Example:

try
{
    //do something or get data from database
}
catch
{
    MessageBox.Show(" No data Found");
}

If you will get record, you can do what ever you want and if there is no data you will see message.    
0
 
malharoneCommented:
           System.Data.DataSet ds=new  System.Data.DataSet("TestDataSet");
            System.Data.SqlClient.SqlConnection conn=new System.Data.SqlClient.SqlConnection("YOUR CONNECTION STRING");
            System.Data.SqlClient.SqlCommand sc= new System.Data.SqlClient.SqlCommand("Select * from faculty",conn);
            System.Data.SqlClient.SqlDataAdapter sda = new  System.Data.SqlClient.SqlDataAdapter(sc);
            sda.Fill(ds);
            if (ds==null || ds.Tables.Count<1 ||ds.Tables[0].Rows.Count<1)
            {
                MessageBox.Show ("Error in data!", "My Application", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            else
            {
                //no error
            }
0
Free Tool: Port Scanner

Check which ports are open to the outside world. Helps make sure that your firewall rules are working as intended.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

 
ptmcompCommented:
@Shriraj:
This is dirty programming unless there must be data and else it's an exceptional application state = exception.
0
 
TheAvengerCommented:
OleDbConnection conn = new OleDbConnection ("connString");
OleDbCommand comm = new OleDbCommand();
comm.CommandText = "SELECT * FROM Table";
comm.Connection = conn;
conn.Open();
OleDbDataReader reader = comm.ExecuteReader();
if (!reader.HasRows)
  do whatever needed when there is no data

while (reader.Read()) {
  do whatever needed with the data;
  it will come here only if data is available
}

reader.Close();
conn.Close();
0
 
SmoerbleAuthor Commented:
Why has "TheAvenger" a complete different code than "malharone"?
Which one is betetr to use when?
0
 
SmoerbleAuthor Commented:
Increased points to 250...
0
 
TheAvengerCommented:
What else do you need? The solution I gave you works fine...
0
 
SmoerbleAuthor Commented:
Please read my comments:
"Why has "TheAvenger" a complete different code than "malharone"?"
I understand that your code works fine, but there has to be a reason why you don't use the SqlDataAdapter... before I change my current code (currently using it), I would like to know _why_ you do it in a different way (I am sure you have a good reason because your other answers in other threads showed good reasons too).

Also please tell me how you would itterate through the result when using your code.
Currently I do it with:

DataSet dtSet = new DataSet();
myCmd.Fill( dtSet, "Developer" );
DataTable dTable = dtSet.Tables[0];foreach( DataRow dtRow in dTable.Rows )
{
   ...
}
0
 
TheAvengerCommented:
Using OleDbXxx objects instead of SqlXxx objects is made when you use an OLE DB provider. SqlXxx object work ONLY with SQL Server (version 7 and above I think), while OleDbXxx work for all OLE DB and ADO.NET supported sources. If you are using SQL Server and you are sure that you will never change to another data source, stay with SqlXxx (just replace the OleDb part with Sql in my code, it will work again).

Using data set and data table is memory and time consuming. If you only need to read the data once, my code iterates over the results in this part:

while (reader.Read()) {
  do whatever needed with the data;
  it will come here only if data is available
}

If you need to access the data later, you should decide how to keep it (maybe put it in an array list or in this case use a DataTable. DataSet is still not needed but can be used as well).
0
 
SmoerbleAuthor Commented:
thanks for the answer. Points granted.
@malharone:
please contact me to recieve additional points even though I don't use your solution.
0
 
BorlandManCommented:

If you have not used a datareader, you should probably be aware of the following:

you can only
- move forward only - cannot move backward in the list.
- and the data is read-only - cannot edit anything.
... but it is very good in performance.


just a friendly fyi


sincerely,
J
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Get your problem seen by more experts

Be seen. Boost your question’s priority for more expert views and faster solutions

  • 4
  • 3
  • 2
  • +3
Tackle projects and never again get stuck behind a technical roadblock.
Join Now