How to fix the connectionstring property has not been initialized - vb.net

Question

I am trying to create a user and insert the data into a MS Access database, but I get an error:
The connectionString property has not been initialized
whenever I click on the button.
I have tried all possible codes on Connection string but the challenge still persist.
Try
Dim sqlconn As New OleDb.OleDbConnection
Dim sqlquery As New OleDb.OleDbCommand
Dim connString As String
connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\PavilionDB.mdb"
sqlquery.Connection = sqlconn
con = New OleDbConnection(conString)
con.Open()
Dim cmd As OleDbCommand = New OleDbCommand(sql, con)
sqlquery.CommandText = "INSERT INTO member(mmbr_id, name, gender, address, phone, join_date, acc_no) VALUES (#txtNewID, #txtName, #txtGender, #txtAddress, #txtPhone, #txtPhone, #)txtAccNo"
sqlquery.Parameters.AddWithValue("New ID", txtNewID.ToString)
sqlquery.Parameters.AddWithValue("Name", txtName.ToString)
sqlquery.Parameters.AddWithValue("Gender", txtGender.ToString)
sqlquery.Parameters.AddWithValue("Address", txtAddress.ToString)
Dim da As New OleDbDataAdapter(cmd)
Dim ds As New DataTable
da = New OleDb.OleDbDataAdapter(sql, con)
da.Fill(ds, "con")
Return
sqlquery.ExecuteNonQuery()
sqlconn.Close()
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try

Answer 1

That code really is a mess. It should be reduced to this and that will fix your issue:
Try
Using connection As New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\PavilionDB.mdb"),
command As New OleDbCommand("INSERT INTO member (mmbr_id, name, gender, address, phone, join_date, acc_no) VALUES (#mmbr_id, #name, #gender, #address, #phone, #join_date, #acc_no)", connection)
With command.Parameters
.AddWithValue("#mmbr_id", txtNewID.Text)
.AddWithValue("#name", txtName.Text)
.AddWithValue("#gender", txtGender.Text)
.AddWithValue("#address", txtAddress.Text)
'Set other parameters here.
End With
connection.Open()
command.ExecuteNonQuery()
End Using
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
Ideally, you would be using Add rather than AddWithValue too, but that's another conversation.

Answer 2

Here is simple code for what you mostly asked for, in addition to the whole open source on this link:
enter link description here
Here is the tested code:
Private Sub BtnAddNewRec_Click(sender As Object, e As EventArgs) Handles BtnAddNewRec.Click
Dim con As New OleDbConnection
Dim cmd As New OleDbCommand
Try
con.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\db1.mdb"
con.Open()
cmd.Connection = con
cmd.CommandText = "INSERT INTO Tbl1 (mmbr_id, name, gender, address) VALUES (#txtNewID, #txtName, #txtGender, #txtAddress)"
cmd.Parameters.AddWithValue("#txtNewID", txtNewID.Text)
cmd.Parameters.AddWithValue("#txtName", txtName.Text)
cmd.Parameters.AddWithValue("#txtGender", txtGender.Text)
cmd.Parameters.AddWithValue("#txtAddress", txtAddress.Text)
cmd.ExecuteNonQuery()
MsgBox("Record Added Successfully!")
Catch ex As Exception
MessageBox.Show("Error while inserting record on table..." & ex.Message, "Insert Records")
Finally
con.Close()
End Try
End Sub
I hope this helps:

Answer 3

The trouble here is that you have 2 commands in your code, namely cmd and sqlquery. You define sqlquery at the beginning of the code, then initialize cmd with the connection and a SQL variable that I cannot determine the source of.
What you need to do is redo this part and get remove the extra references that seem to be the source of the problem. Consider the following...
Try
Dim conString As String
Dim text = "INSERT INTO member(mmbr_id, name, gender, address, phone, join_date, acc_no) VALUES (#txtNewID, #txtName, #txtGender, #txtAddress, #txtPhone, #txtPhone, #)txtAccNo"
conString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\PavilionDB.mdb"
Using sqlCon = New OleDbConnection(conString), sqlCmd = New OleDbCommand(text, sqlCon)
With sqlCmd.Parameters
.AddWithValue("New ID", 234234)
.AddWithValue("Name", "Fabulous")
.AddWithValue("Gender", "Male")
.AddWithValue("Address", "127.0.0.1")
End With
sqlCon.Open()
sqlCmd.ExecuteNonQuery()
End Using
Catch ex As Exception
MsgBox(ex.Message)
End Try
I couldn't tell whether txtNewID and the other similarly named variables are text boxes or not. If they are text boxes, you need the .Text property which gets the content in a string. You'll need to replace the literals I used in my test environment to get to it.
Ensure everything, including your connection string and query are correct for this to run smoothly. In your current case, you are getting the connection string related error because you are attempting to execute the query on a connection you didn't associate with the connection.