Vb.net application

<?xml version="1.0" encoding="utf-8"?>

<configuration>

  <connectionStrings>

    <add name="ConString" connectionString="Data Source=DESKTOP-NH2JKOJ;Initial Catalog=CrystalGallery;Persist Security Info=True;User ID=sa;Password=pass" providerName="System.Data.SqlClient"/>

  </connectionStrings>

    <startup>

        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>

    </startup>

</configuration>

 Imports System.Data.SqlClient

Imports System.Configuration

Public Class Dbmanager

    Public Sub New()

    End Sub

    Function getdata(sqlquery As String) As DataSet

        Using conn As New SqlConnection(ConfigurationManager.ConnectionStrings("ConString").ToString)

            conn.Open()

            Dim da As SqlDataAdapter

            Dim ds As DataSet

            Dim cmd As New SqlCommand(sqlquery, conn)

            cmd.CommandType = CommandType.Text

            da = New SqlDataAdapter(cmd)

            ds = New DataSet

            da.Fill(ds, "Table")

            conn.Close()

            Return ds

        End Using

    End Function

    Function getdatafromprocedure(sqlquery As String) As DataSet

        Using conn As New SqlConnection(ConfigurationManager.ConnectionStrings("ConString").ToString)

            conn.Open()

            Dim da As SqlDataAdapter

            Dim ds As DataSet

            Dim cmd As New SqlCommand(sqlquery, conn)

            cmd.CommandType = CommandType.Text

            da = New SqlDataAdapter(cmd)

            ds = New DataSet

            da.Fill(ds, "Table")

            conn.Close()

            Return ds

        End Using

    End Function

    Function InsertData(sqlquery As String) As Integer

        Using conn As New SqlConnection(ConfigurationManager.ConnectionStrings("ConString").ToString)

            Dim cmd As New SqlCommand(sqlquery, conn)

            conn.Open()

            cmd.ExecuteNonQuery()

            conn.Close()

            Return 1

        End Using

    End Function

    Function getdataforcombo(sqlquery As String) As DataTable

        Using conn As New SqlConnection(ConfigurationManager.ConnectionStrings("ConString").ToString)

            Dim cmd As New SqlCommand(sqlquery, conn)

            conn.Open()

            Dim dt As New DataTable()

            dt.Load(cmd.ExecuteReader)

            conn.Close()

            Return dt

        End Using

    End Function

End Class

Imports System.Data.SqlClient

Imports System.Configuration

Public Class ItemMaster

    Private Sub Button5_Click(sender As Object, e As EventArgs) Handles Button5.Click

        Dim itemcode, itemname, itemdesc, itemdate, itemweight, itemheight, itmsubcategory, itmcategory, querystring As String

        itemcode = txtitemcode.Text

        itemname = txtitemname.Text

        itemdesc = txtitemdesc.Text

        itemdate = dptitemdate.Text

        itemweight = txtweight.Text

        itemheight = txtheight.Text

        itmsubcategory = cmbitemsubcategory.Text

        itmcategory = cmbitemcategory.Text

        querystring = "INSERT INTO ItemMaster(ItemCode,ItemName,ItemDesc,ItemWeight,ItemHeight,ItemCategory,ItemSubcategory,ItemDate) VALUES ('" & itemcode & "', '" & itemname & "','" & itemdesc & "','" & itemweight & "','" & itemheight & "','" & itmcategory & "','" & itmsubcategory & "', '" & itemdate & "') "

        Dim db = New Dbmanager()

        Dim ds As Integer = db.InsertData(querystring)

        Dim dibox As DialogResult = MessageBox.Show("Data saved successfully")

    End Sub

    Private Sub cmbitemcategory_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cmbitemcategory.SelectedIndexChanged

    End Sub

    Private Sub ItemMaster_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Dim querystring As String

        querystring = "select * from ItemCategory"

        Dim db = New Dbmanager()

        Dim dtsubcategory As DataTable = db.getdataforcombo(querystring)

        cmbitemcategory.DataSource = dtsubcategory

        cmbitemcategory.DisplayMember = "CategoryName"

        cmbitemcategory.ValueMember = "CategoryID"

        querystring = "select * from ItemSubcategory"

        Dim dtcategory As DataTable = db.getdataforcombo(querystring)

        cmbitemsubcategory.DataSource = dtcategory

        cmbitemsubcategory.DisplayMember = "Itemsubcategoryname"

        cmbitemsubcategory.ValueMember = "ItemsubcategoryID"

    End Sub

    Private Sub TabPage2_Click(sender As Object, e As EventArgs) Handles TabPage2.Click

        Dim querystring As String

        querystring = "select * from ItemMaster"

        Dim db = New Dbmanager()

        Dim dtitemmaster As DataTable = db.getdataforcombo(querystring)

        DataGridView1.DataSource = dtitemmaster

    End Sub

    Private Sub DataGridView1_CellContentClick(sender As Object, e As DataGridViewCellEventArgs) Handles DataGridView1.CellContentClick

    End Sub

    Private Sub DataGridView1_MouseClick(sender As Object, e As MouseEventArgs) Handles DataGridView1.MouseClick

        Dim querystring As String

        querystring = "select * from ItemMaster"

        Dim db = New Dbmanager()

        Dim dtitemmaster As DataTable = db.getdataforcombo(querystring)

        DataGridView1.DataSource = dtitemmaster

    End Sub

End Class