ADO.NET 查找是否存在表，若存在，删除建立

Imports System.Data.SqlClient

Public Class Form1
    Public constr As String = "Data Source = (localdb)\MSSQLLocalDB; Integrated Security = True ;AttachDbFileName= D:\Database\Local Database\julietest0602.mdf"
    Public conn As SqlConnection
    Public sda As SqlDataAdapter
    Public cmd As SqlCommand
    Public dt As New DataTable
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Using conn = New SqlConnection(constr)
            conn.Open()
            cmd = New SqlCommand("IF EXISTS(Select * From sysobjects Where Name='test') drop table test", conn)
            cmd.ExecuteNonQuery()
            MsgBox("Delete OK!")


            cmd = New SqlCommand("CREATE TABLE test
                    ([CODPRO] NVARCHAR (50) Not NULL, [DESPRO] NVARCHAR (90) NOT NULL,
                    [2017quantity] FLOAT(53) NOT NULL, [2017value] FLOAT(53) NOT NULL, 
                    [2018quantity] FLOAT(53) NOT NULL, [2018value] FLOAT(53) NOT NULL, 
                    [2019quantity] FLOAT(53) NOT NULL, [2019value] FLOAT(53) NOT NULL)", conn)
            cmd.ExecuteNonQuery()
            MsgBox("Create OK!")

            cmd = New SqlCommand("Select * from test ", conn)
            sda = New SqlDataAdapter(cmd)
            Dim dt1 As New DataTable
            sda.Fill(dt1)
            DataGridView1.DataSource = dt1

        End Using
    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Using conn = New SqlConnection(constr)
            conn.Open()
            cmd = New SqlCommand("Select * from test ", conn)
            sda = New SqlDataAdapter(cmd)
            Dim dt1 As New DataTable
            sda.Fill(dt1)
            DataGridView1.DataSource = dt1

        End Using
    End Sub
End Class