SQLDataReader Error

  • Thread starter Thread starter Damian
  • Start date Start date
D

Damian

Hi everyone !

I am having a problem getting the datareader to work. It seems that it
doesnt get instantiated when i Dim it. The locals window when i run
the program has myReader ( the sqldatareader) set to Nothing and it
doesnt change. I tried adding the New keyword but it doesnt Build the
app , it comes up with an error saying it is not accessible in this
context because it is "Private".

Here is the code:

Dim err As Exception
Dim sConnString As String
Dim sql As String
Dim nwindConn As New SqlClient.SqlConnection
Dim authorsCMD As New SqlClient.SqlCommand
Dim myReader As SqlClient.SqlDataReader

sConnString = "Data
Source=sydsql;uid=DBDeveloper;pwd=password;Initial Catalog=northwind;"
sql = "Select au_fname,au_lname from Authors"

Try
nwindConn.ConnectionString = sConnString
nwindConn.Open()
authorsCMD.Connection = nwindConn
authorsCMD.CommandText = sql
myReader = authorsCMD.ExecuteReader() <--- crashes on
this line
If myReader.HasRows Then
Do While myReader.Read()
cboAuthors.Items.Add(myReader.GetString(0))
Loop
End If
Catch
MsgBox("Error occurred: " & err.ToString)
End Try

I am able to connect to the database.The code crashes on the following
line:
myReader = authorsCMD.ExecuteReader(). Says MyReader is set to
nothing.

Any ideas ?

Any help would be appreciated !
 
Hi Damian,

Are you sure about the row?
Seems odd that on assignment it would say that the myReader is nothing.
 
Unless you've changed something, Authors is in the Pubs database, not
Northwind!

Change your connection string, instead of Initial Catalog=northwind, use
Initial Catalog=Pubs

Miha Markic said:
Hi Damian,

Are you sure about the row?
Seems odd that on assignment it would say that the myReader is nothing.

--
Miha Markic [MVP C#] - RightHand .NET consulting & software development
miha at rthand com
www.rthand.com

Damian said:
Hi everyone !

I am having a problem getting the datareader to work. It seems that it
doesnt get instantiated when i Dim it. The locals window when i run
the program has myReader ( the sqldatareader) set to Nothing and it
doesnt change. I tried adding the New keyword but it doesnt Build the
app , it comes up with an error saying it is not accessible in this
context because it is "Private".

Here is the code:

Dim err As Exception
Dim sConnString As String
Dim sql As String
Dim nwindConn As New SqlClient.SqlConnection
Dim authorsCMD As New SqlClient.SqlCommand
Dim myReader As SqlClient.SqlDataReader

sConnString = "Data
Source=sydsql;uid=DBDeveloper;pwd=password;Initial Catalog=northwind;"
sql = "Select au_fname,au_lname from Authors"

Try
nwindConn.ConnectionString = sConnString
nwindConn.Open()
authorsCMD.Connection = nwindConn
authorsCMD.CommandText = sql
myReader = authorsCMD.ExecuteReader() <--- crashes on
this line
If myReader.HasRows Then
Do While myReader.Read()
cboAuthors.Items.Add(myReader.GetString(0))
Loop
End If
Catch
MsgBox("Error occurred: " & err.ToString)
End Try

I am able to connect to the database.The code crashes on the following
line:
myReader = authorsCMD.ExecuteReader(). Says MyReader is set to
nothing.

Any ideas ?

Any help would be appreciated !
Click to expand...
Click to expand...
 
Also, consider using Exception and SQLException instead of the Err object

Catch ex As SqlException

MsgBox("Error occurred: " & ex.Message)

Catch ex As Exception

MsgBox("Error occurred: " & ex.Message)

The first message box now shows "Invalid object name 'Authors'" when using
Northwind


Miha Markic said:
Hi Damian,

Are you sure about the row?
Seems odd that on assignment it would say that the myReader is nothing.

--
Miha Markic [MVP C#] - RightHand .NET consulting & software development
miha at rthand com
www.rthand.com

Damian said:
Hi everyone !

I am having a problem getting the datareader to work. It seems that it
doesnt get instantiated when i Dim it. The locals window when i run
the program has myReader ( the sqldatareader) set to Nothing and it
doesnt change. I tried adding the New keyword but it doesnt Build the
app , it comes up with an error saying it is not accessible in this
context because it is "Private".

Here is the code:

Dim err As Exception
Dim sConnString As String
Dim sql As String
Dim nwindConn As New SqlClient.SqlConnection
Dim authorsCMD As New SqlClient.SqlCommand
Dim myReader As SqlClient.SqlDataReader

sConnString = "Data
Source=sydsql;uid=DBDeveloper;pwd=password;Initial Catalog=northwind;"
sql = "Select au_fname,au_lname from Authors"

Try
nwindConn.ConnectionString = sConnString
nwindConn.Open()
authorsCMD.Connection = nwindConn
authorsCMD.CommandText = sql
myReader = authorsCMD.ExecuteReader() <--- crashes on
this line
If myReader.HasRows Then
Do While myReader.Read()
cboAuthors.Items.Add(myReader.GetString(0))
Loop
End If
Catch
MsgBox("Error occurred: " & err.ToString)
End Try

I am able to connect to the database.The code crashes on the following
line:
myReader = authorsCMD.ExecuteReader(). Says MyReader is set to
nothing.

Any ideas ?

Any help would be appreciated !
Click to expand...
Click to expand...
 
Jim Hughes said:
Also, consider using Exception and SQLException instead of the Err object

Catch ex As SqlException

MsgBox("Error occurred: " & ex.Message)

Catch ex As Exception

MsgBox("Error occurred: " & ex.Message)

The first message box now shows "Invalid object name 'Authors'" when using
Northwind


Miha Markic said:
Hi Damian,

Are you sure about the row?
Seems odd that on assignment it would say that the myReader is nothing.

--
Miha Markic [MVP C#] - RightHand .NET consulting & software development
miha at rthand com
www.rthand.com

Damian said:
Hi everyone !

I am having a problem getting the datareader to work. It seems that it
doesnt get instantiated when i Dim it. The locals window when i run
the program has myReader ( the sqldatareader) set to Nothing and it
doesnt change. I tried adding the New keyword but it doesnt Build the
app , it comes up with an error saying it is not accessible in this
context because it is "Private".

Here is the code:

Dim err As Exception
Dim sConnString As String
Dim sql As String
Dim nwindConn As New SqlClient.SqlConnection
Dim authorsCMD As New SqlClient.SqlCommand
Dim myReader As SqlClient.SqlDataReader

sConnString = "Data
Source=sydsql;uid=DBDeveloper;pwd=password;Initial Catalog=northwind;"
sql = "Select au_fname,au_lname from Authors"

Try
nwindConn.ConnectionString = sConnString
nwindConn.Open()
authorsCMD.Connection = nwindConn
authorsCMD.CommandText = sql
myReader = authorsCMD.ExecuteReader() <--- crashes on
this line
If myReader.HasRows Then
Do While myReader.Read()
cboAuthors.Items.Add(myReader.GetString(0))
Loop
End If
Catch
MsgBox("Error occurred: " & err.ToString)
End Try

I am able to connect to the database.The code crashes on the following
line:
myReader = authorsCMD.ExecuteReader(). Says MyReader is set to
nothing.

Any ideas ?

Any help would be appreciated !
Click to expand...
Click to expand...
Click to expand...

Yeah thanks i used the wrong database...duh! Thanks for tge tip on error handling !
 
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