visual basic设计公用模板，连接数据库代码

以下是一个使用Visual Basic设计公用模板并连接数据库的示例代码：

```vbnet
Imports System.Data.SqlClient

Public Class DatabaseConnection
Private connectionString As String = "你的数据库连接字符串"

Public Function ConnectToDatabase() As SqlConnection
Dim connection As New SqlConnection(connectionString)
Try
connection.Open()
Return connection
Catch ex As Exception
MessageBox.Show("无法连接到数据库： " & ex.Message)
Return Nothing
End Try
End Function

Public Function ExecuteQuery(ByVal query As String) As SqlDataReader
Dim connection As SqlConnection = ConnectToDatabase()
If connection IsNot Nothing Then
Dim command As New SqlCommand(query, connection)
Return command.ExecuteReader()
Else
Return Nothing
End If
End Function

Public Function ExecuteNonQuery(ByVal query As String) As Integer
Dim connection As SqlConnection = ConnectToDatabase()
If connection IsNot Nothing Then
Dim command As New SqlCommand(query, connection)
Return command.ExecuteNonQuery()
Else
Return -1
End If
End Function
End Class
```

请将`你的数据库连接字符串`替换为实际的数据库连接字符串。这个类包含了连接到数据库、执行查询和执行非查询操作的方法。你可以根据需要在你的项目中使用这个类来连接数据库并执行相应的操作。