Question

Access 데이터베이스에 항목이 이미 있는지 확인하고 싶습니다. 그리고 내 연구를 통해이 코드를 얻는 데 성공했지만 오류가 발생했습니다. 원하는 코드를 달성하는 데 올바른 방향으로 나를 안내 할 수 있습니까? 여기

내 코드입니다 :

Dim commandText = "SELECT COUNT(*) AS FROM ESRRegister WHERE ID = '" & IDtxt.Text & "'" 
    Using (conn = New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\Database\Database.accdb")) 
     Using ("select = New OleDbCommand(commandText, conn)") 
      conn.open() 
      Dim count = Convert.ToInt32("select.ExecuteScalar()") 
      If count > 0 Then 
       MessageBox.Show("Already Exists!", "ALI ENTERPRISES", MessageBoxButtons.OK, MessageBoxIcon.Information) 
      Else 'Your insert code cmd.CommandText = "insert into ESRRegister (Dt,ID)VALUES ('" & Dttxt.Text & "' , '" & IDtxt.Text & "')" queryResult = cmd.ExecuteScalar() MsgBox("Added Successfuly") 
      End If 
     End Using 
    End Using 

내가

가 대단히 감사합니다 .NET에 새로 온 사람 bcoz 당신이 코드에 대한 약간의 설명을 제공하는 경우 그것은 좋은 것

Answer 1

'The SQL instruction as a string 
commandText = "SELECT COUNT(*) AS FROM ESRRegister WHERE ID = '" & IDtxt.Text & "'" 
'Open the connection to the Database 
Connection.Open() 
    'Use the SQLinstruction to create an OleDBcommand 
    Dim mySQLCommand As System.Data.OleDb.OleDbCommand = New System.Data.OleDb.OleDbCommand(commandText, Connection) 
    'Perform the SQL-instruction 
    Dim count as integer = CInt(mySQLCommand.ExecuteScalar) 
    mySQLCommand.Dispose() 'Clean the command object 
Connection.Close() 'Close/Clean connection 

Answer 2

Dim commandText As String = "SELECT NZ(COUNT(*),0) FROM ESRRegister WHERE ID = '" & IDtxt.Text & "'" 
Using conn as New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=D:\Database\Database.accdb") 
dim Cmd As New OleDbCommand(commandText, conn 
    conn.open() 
    Dim count as intiger = Convert.ToInt32(Cmd.ExecuteScalar()) 
    If count > 0 Then 
     MessageBox.Show("Already Exists!", "ALI ENTERPRISES", MessageBoxButtons.OK, MessageBoxIcon.Information) 
    Else 
     cmd.CommandText = "insert into ESRRegister (Dt,ID)VALUES ('" & Dttxt.Text & "' , '" & IDtxt.Text & "')" 
     Dim queryResult as Variant = cmd.ExecuteNonQueryr() 
     MsgBox("Added Successfuly") 
    End If 
End Using 

select는 VB.net에 저장된 단어, 나는 OleDbCommand의 이름을하는 변경 Cmd