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The DataSet result is always empty in C#

I am retrieving particular column value using DataSet.
This is my code:
public DataSet GetRedirectURL(string emailId)
{
DataSet ds = new DataSet();
using (SqlConnection con = new SqlConnection(#"Connection_String_Here"))
{
con.Open();
SqlCommand sqlComm = new SqlCommand("usp_Login", con)
{
CommandType = CommandType.StoredProcedure
};
sqlComm.Parameters.AddWithValue("#EmailId", emailId);
SqlDataAdapter da = new SqlDataAdapter
{
SelectCommand = sqlComm
};
da.Fill(ds);
}
return ds;
}
I have also used DataTable instead of it but the same result.
I have checked my Stored Procedure and when I pass Parameter it shows Data. So, nothing wrong with the SP. But the Table doesn't show any data and is always empty as shown below:
What am I missing? Any help would be appreciated.

I'd suggest you to first evaluate the content of your DataSet. For instance, type in your Immediate Window (or add a quick watch) to check ds.Tables[0].Rows.Count. Basically, to assert your DataSet has been properly filled with the contents fetched from the database, and focus on the data assignment from the DataSet to the grid object you're using to display it.
Also, the .Fill() method has a returning object which is an int representing the amount of rows that have been successfully filled into the target object. For instance:
int result = da.Fill(ds);
Check the value of result after the .Fill() method has been executed.
Finally, I guess you're using a DataGridView object to visualize the results. If so, how are you binding data? Should be something like:
dataGridView1.DataSource = ds.Tables[0];
PS: As I've read in other comments, no, you don't need to execute the .Open() method on the connection. That's not necesarry, it's done implicitely when using the (using SqlConnection conn = SqlConnection..)

Using an SqlDataAdapter with a stored procedure and parameters to update as well as retrieve values

In How to use a DataAdapter with stored procedure and parameter, the data adapter's selectCommand property has been used. Can the same be used if a stored procedure updates as well as retrieves data from a database?

On implementing it, and using the selectCommand (and not the property, it seems to work alright.
...
SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlQuery, sqlConnection);
foreach (SqlParameter sqlParameter in sqlParameterCollection)
{
sqlCommand.Parameters.Add(new SqlParameter(sqlParameter.ParameterName, sqlParameter.Value));
}
sqlDataAdapter.SelectCommand = sqlCommand;
DataSet dataSet = new DataSet();
sqlDataAdapter.Fill(dataSet);
...

The short answer is yes. Passing parameters to a stored procedure which updates and returns values is no different from the SqlDataAdapter side compared to a stored procedure that only returns values based on parameters passed in.

Execute a stored procedure using an SqlDataAdapter in C#

How can i use an SqlDataAdapter to execute an sql stored procedure that contains statements which update one table and insert into another table, but returns no value?
EDIT:There are answers related to the execution of stored procedures with SELECT statements. However, that's not what i'm looking for.

I'm assuming you're using the SqlDataAdapter to populate a DataTable or DataSet object. If this is the case and you want the changes to the DataTable/DataSet to be persisted to your database and you require using stored procs then you'd need to set the UpdateCommand, InsertCommand, and/or DeleteCommand properties.
Example:
SqlDataAdapter adapter = new SqlDataAdapter("SELECT * FROM WHATEVER", connection);
adapter.UpdateCommand = new SqlCommand()
{
Connection = connection,
CommandText = "EXEC myStoredProc",
CommandType = CommandType.StoredProcedure
};
//Don't forget to set your parameters!
Otherwise if you don't need the adapter just use a SqlCommand and call ExecuteNonQuery()

If the statement returns no data, you wouldn't use a SqlDataAdapter. Just use a SqlCommand and call ExecuteNonQuery().

Access results of SQL Server stored functions in C#

I have created a few stored functions in SQL Server that return a table via a select statement. Like so:
CREATE FUNCTION [dbo].[mFunSelectStudents] ()
RETURNS #result TABLE
(IDStudent int,
Name nchar(50),
Password nchar(50))
AS
BEGIN
INSERT INTO #result select * from School.dbo.Student
RETURN
END
I tried to assign the function to an SqlDataAdapter in c# like this:
SqlCommand cmd = new SqlCommand("mFunSelectStudents", con);
SqlDataAdapter adpStudents = new SqlDataAdapter();
adpStudents.SelectCommand = cmd;
But this doesn't work..
Where #result is a return parameter of the stored function. Now, how do I call the function in C# and assign the data to a grid ?
Any help is appreciated..

The command cannot be just the name of the function. You are supposed to put a SQL command there, and in SQL one retrieves data from a TVF by SELECTing from it, like this:
SELECT * FROM dbo.mFunSelectStudents()
Consequently, the first line of your C# code snippet should be:
SqlCommand cmd = new SqlCommand("SELECT * FROM dbo.mFunSelectStudents()", con);

Wrap the function in a stored procedure, or do the work itself in a SP. The results of a single select statement will be accessible as a DataTable in the C# client.
create proc selectSomeData
.
.
.
In the client, your commandType would be StoredProcedure and the CommandText would be the name of the sp.

Your first line :
SqlCommand cmd = new SqlCommand("mFunSelectStudents", con);
Is correct, however this one you should check it
SqlDataAdapter adpStudents.SelectCommand = cmd;
First you need to use new with the SqlDataAdapter before you can assign the selectCommand, as follows:
SqlDataAdapter adpStudents = new SqlDataAdapter(cmd);
Assign the command to the DataAdapter
adpStudents.SelectCommand = cmd;
And then you prepare a Dataset
DataSet ds = new DataSet();
Fill it with your DataAdapter
adpStudents.Fill(ds);
Assign it to your grid
gridName.DataSource = ds;
And call DataBind to update the info on the grid
gridName.DataBind();

Help with DataAdapter - DB doesn't update?

I have a data adapter. When I check the function at runtime I see the changes, but nothing happens in the database. How do I debug this? What went wrong?
OleDbDataAdapter adapter = new OleDbDataAdapter();
string queryString = "SELECT * FROM tasks";
OleDbConnection connection = new OleDbConnection(cn.ConnectionString);
adapter.SelectCommand = new OleDbCommand(queryString, connection);
OleDbCommandBuilder builder = new OleDbCommandBuilder(adapter);
connection.Open();
adapter.Fill(ds.Tables["Tasks"]);
adapter.Update(ds);
return ds;

Nothing is happening in the database because you're running a SELECT query. What are you expecting to happen?

Well unless you snipped a lot of code, you are not changing anything in the dataset per se.
What are you trying to achieve?
Here, you are selecting some data, filling the dataset with it, then putting back the unchanged dataset in the DB.
You should first change something in the dataset itself before calling adapter.Update(ds)
Cheers,
Florian

You are selecting data via the SelectCommand. If you want to update data, you need to run the UpdateCommand.

I assume you didn't post the full source code, as it looks as though you're not modifying the dataset. However, I just tweaked your code a bit (see my comments).
Hopefully this will help...
string queryString = "SELECT * FROM tasks";
OleDbConnection connection = new OleDbConnection(cn.ConnectionString);
connection.Open(); // open connection first
SqlCommand cmd = new SqlCommand(queryString, connection);
OleDbDataAdapter adapter = new OleDbDataAdapter(cmd); // use the cmd above when instantiating the adapter
OleDbCommandBuilder builder = new OleDbCommandBuilder(adapter);
adapter.Fill(ds.Tables["Tasks"]);
// Modify your dataset here.
// Don't call AcceptChanges() as this will prevent the update from working.
adapter.Update(ds);
connection.Close(); // Close connection before ending the function
return ds;
This should allow OleDbCommandBuilder to do its thing by automatically scripting the database updates.

As far as I can see you've not actually changed any of the contents of the tasks table. When you call adapter.Fill you are populated the empty dataset with the records from the database. You are then calling adapter.Update without changing any records within the dataset. The update command only performs changes when the dataset > datatable > datarows are edited and marked as dirty.

you are only specifying the select command. you also need to specify the insert command... i.e:
DataAdapter.InsertCommand = new OleDbCommand....