如何在导入vb.net时检查数据库中的重复值

Imports System.Data.SqlClient

Public Class Form1
    Private Sub btnImport_Click(sender As Object, e As EventArgs) Handles btnImport.Click
        Dim connectionString As String = "Data Source=YourServer;Initial Catalog=YourDatabase;User ID=YourUsername;Password=YourPassword"
        Dim query As String = "SELECT COUNT(*) FROM YourTable WHERE YourColumn = @Value"

        Using connection As New SqlConnection(connectionString)
            connection.Open()

            Using command As New SqlCommand(query, connection)
                command.Parameters.AddWithValue("@Value", txtValue.Text)

                Dim count As Integer = CInt(command.ExecuteScalar())

                If count > 0 Then
                    MessageBox.Show("Duplicate value found in the database.")
                    ' 可以执行其他操作，如清空输入框或要求用户更改值
                Else
                    ' 可以继续导入操作
                End If
            End Using
        End Using
    End Sub
End Class