選擇隨機記錄並將記錄標記爲正在使用

Question

因此，以下選擇要使用的隨機組。一旦被選中，我將這個團隊標記爲Used字段中的X，並在稍後使用更新查詢。對於它最有效的，但經過這幾次，我開始得到重複的團隊，即使他們被標記爲X.

我還錯過了什麼來完成呢？

這裏是SQL語句：

SELECT TOP 1 RandomTeams.[Team Name], RandomTeams.Used 
FROM RandomTeams 
WHERE (((RandomTeams.Used) Is Null)) 
ORDER BY Rnd(TeamID); 

這裏是我是如何處理的更新標記一個團隊正在使用，這是按預期工作，我有X標記的時候，這裏沒有任何問題：

Text214.Text包含正在使用

strTeam = (Chr(34) + Text214.Text + (Chr(34))) 

strSQLUpdateTeams = "UPDATE RandomTeams SET Used = 'X' WHERE [Team Name] = " & strTeam 

DoCmd.SetWarnings (WarningsOff) 
DoCmd.RunSQL strSQLUpdateTeams 

Answer 1

作爲測試，如何只拋出下面的代碼模塊，然後執行它，看看會發生什麼的隊名。順便說一句，你如何重置[使用]？

Sub Test_Teams() 
    Dim strSQL  As String 
    Dim strTeam  As String 
    Dim strSQLUpdateTeams As String 
    Dim dbs   As DAO.Database 
    Dim rs   As DAO.recordSet 

    Set dbs = CurrentDb 
    If MsgBox("Do you want to reset all 'Used' flags?", vbYesNo, "Reset?") = vbYes Then 
     strSQL = "update RandomTeams set [Used] = null;" 
     dbs.Execute strSQL 

    End If 
MyLoop: 
    strSQL = "SELECT TOP 1 RandomTeams.[Team Name], RandomTeams.Used " & _ 
      "FROM RandomTeams " & _ 
      "WHERE (((RandomTeams.Used) Is Null)) " & _ 
      "ORDER BY Rnd(TeamID);" 

    Set rs = dbs.OpenRecordset(strSQL) 
    If Not rs.EOF Then 
     strTeam = rs![Team Name] 
     Debug.Print "Found Team: " & strTeam 
    Else 
     MsgBox "EOF! No more teams." 
     rs.Close 
     Set rs = Nothing 
     dbs.Close 
     Set dbs = Nothing 
     Exit Sub 
    End If 
    strTeam = (Chr(34) + rs![Team Name] + (Chr(34))) 
    rs.Close 
    Set rs = Nothing 

    strSQLUpdateTeams = "UPDATE RandomTeams SET [Used] = 'X' WHERE [Team Name] = " & strTeam 
    Debug.Print strSQLUpdateTeams 
    'DoCmd.SetWarnings (WarningsOff) 
    'DoCmd.RunSQL strSQLUpdateTeams 
    dbs.Execute strSQLUpdateTeams 
    If dbs.RecordsAffected <> 1 Then 
     MsgBox "Whoa! Not good! Update failed!" 
    End If 
    GoTo MyLoop 


End Sub