Break in dubugger not "working".. code execution continues

Question

I have a winforms project which depends on a custom library. Everything with the app is working fine except a problem I can not pin down. Basically I have a form which is created from another form which displays it as a dialog:

DataItems.ImportForm frmImportTextDelimited = new DataItems.ImportForm();
frmImportTextDelimited.ShowDialog();

This dialog form populates a dropdown list from the SqlServer using the below function which is from a class library in the solution:

public class AuthorityTypeSearcher
{
    public List<IntValuePair> GetAllAuthorityTypes()
    {
        List<IntValuePair> returnList = new List<IntValuePair>();
        using (var conn = new SqlConnection(Globals.ConnString))
        {
            var cmd = new SqlCommand();
            cmd.Connection = conn;
            cmd.CommandText = "SELECT FROM tblAuthorityTypes";
            conn.Open();
            IntValuePair ivp;
            SqlDataReader rdr = cmd.ExecuteReader();
            while (rdr.Read())
            {
                ivp = new IntValuePair();
                ivp.TheInt = Convert.ToInt32(rdr["ID"]);
                ivp.TheValue = rdr["AuthorityType"].ToString() ;
            }
        }
        return returnList;
    }

This function never returns a value, so I set a breakpoint on the line:

            conn.Open();

When the code executes, the Visual studio correctly breaks to this line. What is making me crazy is that when I step forward to the line:

            SqlDataReader rdr = cmd.ExecuteReader();

The debugger will not move forward to the next line, and code execution appears to return to the UI (the form is displayed). What is also strange is that if I interact with the form (i.e. click a button on the form which populates another field), the debugger breaks again, I return to visual studio, which correctly "breaks" to the line related to that operation. It seems like, for whatever reason, when I get to the line that creates the data reader, code execution simply "leaves" the library and returns to the winforms app.

When code execution appears to have returned to the UI, if I return to visual studio it appears that code execution is continuing, at least I can not click "continue" (play). The code execution is not "paused".

What is also strange is that if I close the form (dialog), it breaks back into the debugger on the line from the main form on the line:

frmImportTextDelimited.ShowDialog();

as though I were still debugging.

Hopefully this makes sense? I can't figure out why, when debugging, I cant step past the line where I create the data reader, and why code execution goes back to the UI, but returns to the debugger with the dialog is closed. No error is ever thrown.

Thanks for any advice!

Is it Just a typo? Your sql query doesn't have the column list to return. — Steve, Nov 22 '13 at 21:00
You have `"SELECT FROM tblAuthorityTypes"` as your query. Did you mean something like, `"SELECT * FROM tblAuthorityTypes"`? — Brian, Nov 22 '13 at 21:03
Typo but for kicks I updated it to "SELECT ID, AuthorityType FROM tblAthorityTypes" with the same results. — rune711, Nov 22 '13 at 21:04

score 4 · Accepted Answer · edited May 23 '17 at 11:51

4

The explanation of this behavior lies in the behavior of 64 bit code when an exception is raised during Form_Load.

The syntax of your query is wrong. You don't have a column list and this raise a syntax error by your database engine.

But an exception raised during a Form_Load in a 64 bit environment cannot be trapped by the debugger.

A more detailed answer could be found here

You could try to fix your query adding the appropriate field names (or a star * for all fields).
Also try to run your code outside the Visual Studio IDE. You should see the Exception somewhere.

edited May 23 '17 at 11:51

Community

1
1

answered Nov 22 '13 at 21:05

Steve

213,761
22
232
286

1

AH! Outstanding. I had two errors with the syntax in the SQL statement (I had tried editing the columnnames but mistyped "AuthorityTypes" as "AuthorityType") Since no error ever got thrown I had no idea. I didn't realize this caveat of 64 bit apps. Many many thanks. I was beginning to lose my mind. – rune711 Nov 22 '13 at 21:16
Don't need tell me how you do feel about this. :-) I have already been there- – Steve Nov 22 '13 at 21:20

score 1 · Answer 2 · answered Nov 22 '13 at 21:03

1

Try putting your code in a try catch block and have a look at the inner exception. Also should'nt it be SELECT * FROM tablename?

answered Nov 22 '13 at 21:03

Sourav 'Abhi' Mitra

2,390
16
15

+1 because adding the try/catch did show the error although the basic confusion was the issue Steve explained. – rune711 Nov 22 '13 at 21:15

Break in dubugger not "working".. code execution continues

2 Answers2