英文:
is it necessary to use using Dispose the connection , open and close connection if using DbContext dapper in MS access database on vb.net
问题
以下是翻译好的部分:
"使用 DbContext 在 VB.NET 中的 MS Access 数据库中使用 Dapper 是否需要使用 Dispose 连接、打开和关闭连接?
这是我第一次使用 Dapper,请指导我以确保在执行 CRUD 操作时没有错误,并且高效地使用 OleDb 数据库中的 Dapper。我也担心我的代码实现中可能存在错误。
谢谢。
' 模型
Public Class User
Public Property Id() As Integer
Public Property Name() As String
Public Property Email() As String
Public Property Password() As String
End Class
' 数据库
Public Module DbContext
Public Function GetOledbConnectionString() As String
Return "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\dapperdemo.accdb;Persist Security Info=False;"
End Function
End Module
Public Class UserService
Private ReadOnly _conn As OleDbConnection
Private _connectionString As String = DbContext.GetOledbConnectionString()
Public Sub New()
_conn = New OleDbConnection(_connectionString)
End Sub
Public Function GetUser() As IEnumerable(Of User)
Dim sql = "SELECT * FROM Users"
Dim result = Me._conn.Query(Of User)(sql).ToList()
Return result
End Function
Public Sub InserUser(ByVal user As User)
Dim sql = $"INSERT INTO users
(Name
, Email
, Password
) VALUES ('{user.Name}', '{user.Email}', '{user.Password}');"
Me._conn.Execute(sql)
End Sub
End Class
' 在 DataGridView 中加载数据的窗体加载
Partial Public Class Pguser
Inherits UserControl
Private uService As New Database.UserService()
Public Sub New()
If Program.IsInDesignMode(Me) Then
Return
End If
InitializeComponent()
LoadData()
End Sub
Private Sub LoadData()
Dim user = uService.GetUser()
grid.DataSource = user
End Sub
End Class"
英文:
is it necessary to use using Dispose the connection, open and close connection if using DbContext dapper in MS access database on vb.net.
This is my first time using dapper, please guide me so that there are no errors in doing the crud and efficiently use Dapper in oledb database access.
and also I'm afraid there is an error in implementing my code.
Thanks
'model
Public Class User
Public Property Id() As Integer
Public Property Name() As String
Public Property Email() As String
Public Property Password() As String
End Class
'Database
Public Module DbContext
Public Function GetOledbConnectionString() As String
Return "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\dapperdemo.accdb;Persist Security Info=False;"
End Function
End Module
Public Class UserService
Private ReadOnly _conn As OleDbConnection
Private _connectionString As String = DbContext.GetOledbConnectionString()
Public Sub New()
_conn = New OleDbConnection(_connectionString)
End Sub
Public Function GetUser() As IEnumerable(Of User)
Dim sql = "SELECT * FROM Users"
Dim result = Me._conn.Query(Of User)(sql).ToList()
Return result
End Function
Public Sub InserUser(ByVal user As User)
Dim sql = $"INSERT INTO `users` (`Name`, `Email`, `Password`) VALUES ('{user.Name}', '{user.Email}', '{user.Password}');"
Me._conn.Execute(sql)
End Sub
'form load in datagridview
Partial Public Class Pguser
Inherits UserControl
Private uService As New Database.UserService()
Public Sub New()
If Program.IsInDesignMode(Me) Then
Return
End If
InitializeComponent()
LoadData()
End Sub
Private Sub LoadData()
Dim user = uService.GetUser()
grid.DataSource = user
End Sub
End Class
答案1
得分: 1
关于您的请求:
>请指导我...在oledb数据库访问中有效地使用Dapper
在提到效率之前,正确使用实现IDisposable接口的对象应该是首要考虑的事情。有关Dapper的更多信息,请参阅此答案。看起来Dapper会自动为您打开(和关闭)连接,但由于您正在进行打开操作,那么您也可以同时进行关闭操作。
Public Class UserService
Public Function GetUser() As IEnumerable(Of User)
Using _conn = New OleDbConnection(DbContext.GetOledbConnectionString())
Return _conn.Query(Of User)("SELECT * FROM Users").ToList()
End Using
End Function
Public Sub InserUser(ByVal user As User)
Using _conn = New OleDbConnection(DbContext.GetOledbConnectionString())
_conn.Execute($"INSERT INTO `users` (`Name`, `Email`, `Password`) VALUES ('{user.Name}', '{user.Email}', '{user.Password}');")
End Using
End Sub
End Class
使用 Try ... Finally
Public Function GetUser() As IEnumerable(Of User)
Dim _conn = New OleDbConnection(DbContext.GetOledbConnectionString())
Try
Return _conn.Query(Of User)("SELECT * FROM Users").ToList()
Finally
_conn?.Dispose()
End Try
End Function
您可以使用 Try ... Finally
显式关闭连接,但是使用 Using
语法更加简洁。
您还可以考虑使用Entity Framework来摆脱文本命令的使用。
英文:
About your request
>please guide me... efficiently use Dapper in oledb database access
Properly using the object which implements IDisposable should come before you mention efficiency. See this answer for more info about Dapper specifically. It seems Dapper will open (and close) the connection for you but since you are doing the opening, you might as well do both.
Public Class UserService
Public Function GetUser() As IEnumerable(Of User)
Using _conn = New OleDbConnection(DbContext.GetOledbConnectionString())
Return _conn.Query(Of User)("SELECT * FROM Users").ToList()
End Using
End Function
Public Sub InserUser(ByVal user As User)
Using _conn = New OleDbConnection(DbContext.GetOledbConnectionString())
_conn.Execute($"INSERT INTO `users` (`Name`, `Email`, `Password`) VALUES ('{user.Name}', '{user.Email}', '{user.Password}');")
End Using
End Sub
End Class
With Try ... Finally
Public Function GetUser() As IEnumerable(Of User)
Dim _conn = New OleDbConnection(DbContext.GetOledbConnectionString())
Try
Return _conn.Query(Of User)("SELECT * FROM Users").ToList()
Finally
_conn?.Dispose()
End Try
End Function
You can explicitly close with a Try ... Finally
but the Using
syntax is much cleaner.
You can also look into Entity Framework to move away from text commands.
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