更新远程访问服务器

Question

在创建我的程序时，我发现为包提供本地数据库将更可靠，而不是连接到每个实例的远程数据库。

下面是我的想法如何做到这一点，但我希望它自动发生每个不同的主机，它发现，而不是选择每个成员，并按下按钮。这是我不知道如何实现的。

Imports System.Data.OleDb 

Public Class Form1  
Dim con as oledbconnection = new oledbconnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source='.\localDB.accdb'") 
Dim rem as oledbconnection = new oledbconnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source='\\server\remote.accdb'") 
dim da as new oledbdataadaptor 
dim dt as new datatable 
dim dt2 as new datatable 
Dim Str as string 
Dim cmd as new oledbcommand(str, con) 

Private Sub Form1_load 
con.open() 
da.SelectCommand = New OleDbCommand("select distinct Host from Logs") 
da.fill(dt) 
con.close 

Combobox1.datasource = dt 
Combobox1.displaymember = "Host" 

End Sub 

Private Sub button1_click 
con.open() 
Dim cmd As New OleDbCommand("select * from local where host=@host;", con) 
cmd.parameters.addwithvalue("@host", combobox1.text.tostring) 
da.fill(dt2) 
con.close() 

rem.open() 
Dim cmd1 As New OleDbCommand("update remote set col1=@col1 where ID=@ID;", con) 

cmd1.parameters.addwithvalue("@col1", dt2.rows(0).item(1).tostring) 
cmd1.parameters.addwithvalue("@ID", dt2.rows(0).item(0).tostring) 
rem.close() 

End Sub 
End Class 

任何想法的将不胜感激。 *作为说明，我知道JET提供了同步功能，但是数据库必须采用2007-10格式，所以ACE是唯一的选择。

Answer 1

首先OleDbCommand不接受命名参数，所以您需要引用它们与?并按照它们出现的顺序传递参数。

Dim cmd As New OleDbCommand("select * from local where host = ?", con) 
cmd.parameters.Add(combobox1.Text.ToString) 

一旦这样做，你需要填写DataSet与SQL语句的结果

Dim DA As New OleDbDataAdapter(cmd) 
    Dim DS As New DataSet 
    DA.Fill(DS, "hosts") 

UPDATE

为了有一个等效的代码是你的，我会做这样的事情

Imports System.Data.OleDb 

Public Class Form1 

Dim con as oledbconnection = new oledbconnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source='.\localDB.accdb'") 
Dim rem as oledbconnection = new oledbconnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source='\\server\remote.accdb'") 

dim dt as New DataTable 
Dim Str as String 
Dim cmd as New OleDbCommand(str, con) 


Private Sub Form1_load 

con.open() 
da.SelectCommand = New OleDbCommand("select distinct Host from Logs") 
da.fill(dt) 
con.close 


For Each DR as DataRow In DT.Rows 

con.open() 
Dim cmd As New OleDbCommand("select * from local where host= ? ", con) 
cmd.Parameters.Add(DR.Item(0)) 
Dim DA As New SqlClient.SqlDataAdapter(cmd) 
Dim DS As New DataSet 
da.Fill(DS,"hosts") 
con.close() 

rem.open() 
Dim cmd As New OleDbCommand("update remote set col1=? where ID=?", rem) 

cmd.Parameters.Add(DS.Tables("hosts").Rows(0).Item(1).ToString) 
cmd.Parameters.Add(DS.Tables("hosts").Rows(0).Item(0).ToString) 
cmd.ExecuteNonQuery() 
rem.close() 

Next 

End Sub 
End Class