Database only adds (x) amount of rows before error system resources exceeded - database

Question

I am having a problem with my code where i am only able to add so many lines of text before i get an error "system resources exceeded".
This is my code:
Dim x As Integer = MsgBox("Update Record?", MsgBoxStyle.YesNo, "Are you sure?")
If x = MsgBoxResult.Yes Then
Dim accessconn As New _
System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & "MyDB.accdb")
Dim com As System.Data.OleDb.OleDbCommand
accessconn.Close()
Try
For Each strLine As String In TextBox1.Text.Split(vbNewLine)
accessconn.Open()
Dim str As String
Dim dr As OleDbDataReader
str = "SELECT * FROM Table4 WHERE MD5='" & strLine & "'"
Dim cmd As OleDbCommand = New OleDbCommand(str, accessconn)
dr = cmd.ExecuteReader
If dr.Read() Then
Label2.Text = Label2.Text + 1
Else
accessconn.Open()
com = New System.Data.OleDb.OleDbCommand("INSERT INTO Table4(MD5) VALUES('" & strLine & "')", accessconn)
com.ExecuteReader(CommandBehavior.CloseConnection)
Label3.Text = Label3.Text + 1
com.Dispose()
accessconn.Close()
End If
Next
accessconn.Close()
Catch ex As Exception
MsgBox(ex.ToString)
End Try
MsgBox("Done")
PopulateGridview4()
End If
I would like to be able to add unlimited rows of text to the database if possible. Please Help.

Answer 1

You should change your code to something like the following. Note that
Everything that returns an object like OleDbConnection, OleDbCommand, or OleDbDataReader is wrapped in a Using block. These objects all implement the IDisposable interface, which means they should be cleaned up as soon as you're done with them.
Also note that your INSERT did not return any data, so you should use ExecuteNonQuery instead of ExecuteReader.
Finally, please don't get into the habit of putting Try/Catch/End Try blocks around everything. You were displaying the exception (you displayed ex.ToString, which is a good thing), but you then ignored the exception. As a good general rule, don't catch exceptions unless you can fix them.
Code:
Dim x As Integer = MsgBox("Update Record?", MsgBoxStyle.YesNo, "Are you sure?")
If x = MsgBoxResult.Yes Then
Using accessconn As New _
System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & "MyDB.accdb")
accessconn.Open()
For Each strLine As String In TextBox1.Text.Split(vbNewLine)
Dim str As String = "SELECT * FROM Table4 WHERE MD5='" & strLine & "'"
Using cmd As OleDbCommand = New OleDbCommand(str, accessconn)
Using dr As OleDbDataReader = cmd.ExecuteReader
If dr.Read() Then
Label2.Text = Label2.Text + 1
Else
Using com As OleDbCommand = New System.Data.OleDb.OleDbCommand("INSERT INTO Table4(MD5) VALUES('" & strLine & "')", accessconn)
com.ExecuteNonQuery()
End Using
Label3.Text = Label3.Text + 1
End If
End Using
End Using
Next
MsgBox("Done")
PopulateGridview4()
End Using
End If
P.S. you could probably have made this a little less indented by using If x <> MsgBoxResult.Yes Then get out, but I don't know if this is inside of a Sub or Function, so "get out" could be different.