選擇查詢，需要額外的where子句？

Question

我有一個返回所選歌曲的人的名單時，他們都知道這首歌，狀態爲完成查詢。

有沒有辦法，只顯示歌曲在狀態完成後，當所有的儀器都放不爲「N/A」？

例如，假設該表內容如下之一。

 
    BandieName SongName Instrument Status 
    Holly  Wipeout  Bells  Complete 
    Holly  Centenial N/A   Complete 
    Charlotte Wipeout  Symbols  Complete 
    Charlotte Centenial N/A   Complete 

，如果我從列表中選擇冬青和夏洛特，並運行該查詢，它會列出不經意的和森田，因爲它們都具有這些歌曲作爲狀態的完整;不過，我不希望它顯示森田因爲所有這首歌所選擇的人有文書N/A。

如果內容如下，並且我選擇了其中的三個，我希望它顯示所有三首歌曲，因爲並非所有列出的歌曲都是N/A。

 
    BandieName SongName Instrument Status 
    Holly  Wipeout  Bells  Complete 
    Holly  Centenial N/A   Complete 
    Charlotte Wipeout  Symbols  Complete 
    Charlotte Centenial N/A   Complete 
    Ryan  Wipeout  Drum  Complete 
    Ryan  Centenial Drum  Complete 

我的代碼到目前爲止是以下一個。

Protected Sub btnGetPlaylist_Click(sender As Object, e As System.EventArgs) Handles btnGetPlaylist.Click 

    Dim conn As SqlConnection = Nothing 
    Try 
     Dim connString As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\BandDatabase.mdf;Integrated Security=True;User Instance=True" 
     conn = New SqlConnection(connString) 

     Dim sqlBandies As String 

     Dim item As ListItem 
     For Each item In ListBoxBandies.Items 
      If item.Selected Then 

       Dim selectedBandies As String = item.Text 
       sqlBandies &= "'" & item.Text & "', " 

      End If 
     Next 

     Dim amountSelected As String = ListBoxBandies.Items.Count.ToString 


     Dim query As String = "select SongName from Learning where BandieName in (" + sqlBandies + " '') AND Status = 'Complete' group by SongName having count(distinct BandieName) = " + ListBoxBandies.GetSelectedIndices.Length.ToString 

     Dim cmd As SqlCommand = New SqlCommand(query, conn) 

     conn.Open() 
     Dim dr As SqlDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection) 
     Dim dt As DataTable = New DataTable() 
     dt.Load(dr) 
     GridViewPlaylist.DataSource = dt 
     GridViewPlaylist.DataBind() 


    Finally 
     conn.Close() 
    End Try 

End Sub 

Answer 1

如果你的意思是找到的所有歌曲，所有指定名稱的歌曲和狀態完全和它們中的至少一個（但不一定是全部）具有非「N/A」值作爲工具，那麼你可以做幾種方法之一，例如：

select s.SongName 
from Learning s 
    left outer join Learning specInstrument on specInstrument.SongName = s.SongName and specInstrument.BandieName = s.BandieName and specInstrument.Instrument <> 'N/A' 
where s.BandieName in ('Holly', 'Charlotte') 
    and s.Status = 'Complete' 
having count (distinct s.BandieName) = 2 
and count(specInstrument.SongName) > 0 

或者找到具有填充儀器匹配的品牌之一，並鏈接到所有匹配的歌曲：

select s.SongName 
from Learning s 
inner join (select SongName from Learning where status = 'Complete' and BandieName in ('Holly', 'Charlotte') and instrument <> 'N/A') hasInstr on hasInstr.SongName = s.SongName 
where s.BandieName in ('Holly','Charlotte') 
and status = 'Complete' 
group by s.SongName 
having count(distinct s.BandieName) = 2 

很顯然，你已經建立的名單要檢查的名稱以及我已替換的值的相應計數名稱但這顯示了原則。

Answer 2

SELECT 
    BandName 
    , SongName 
    , Instrument 
    , Status 
FROM Learning as l1 
INNER JOIN (
       Select 
        BandName 
        , SongName 
       FROM Learning 
       WHERE Instrument <> 'N/A' AND Status = 'Complete' 
      ) AS l2 
    ON l1.BandName = l2.BandName AND l1.SongName = l2.SongName 

Answer 3

這可能不是最有效的搜索，但它應該工作。稍後我可以嘗試考慮更高效的解決方案。

SELECT DISTINCT SongName 
FROM Learning l1 
WHERE 
    EXISTS (
     SELECT * 
     FROM Learning l2 
     WHERE l1.BandieName = '<First selected BandieName>' 
      AND l1.SongName = l2.SongName 
      AND l2.Status = 'Complete') 
    AND EXISTS (
     SELECT * 
     FROM Learning l3 
     WHERE l1.BandieName = '<Second selected BandieName>' 
      AND l1.SongName = l3.SongName 
      AND l3.Status = 'Complete') 
    -- Repeat these for however many people are selected. 
    AND EXISTS (
     SELECT * 
     FROM Learning lInstrument 
     WHERE NOT lInstrument = 'N/A' 
      AND l1.SongName = lInstrument.SongName 
      AND BandieName IN (<BandieName list>) 
      AND lInstrument.Status = 'Complete') 

Answer 4

您的查詢將是：

WITH LearningCTE AS 
( SELECT * 
    FROM Learning 
    WHERE BandieName IN ('Holly', 'Charlotte', 'Ryan') 
    AND  Status = 'Complete' 
) 
SELECT * 
FROM LearningCTE a 
WHERE EXISTS 
     ( SELECT 1 
      FROM LearningCTE b 
      WHERE a.SongName = b.SongName 
      AND  Instrument != 'N/A' 
     ) 

如果您使用SQL Server 2008我reccomend使用表參數，而不是動態建立在VB.NET你的SQL，它消除了SQL的任何風險注射。你需要做的是這樣的情況如下：

CREATE TYPE NameList AS TABLE (Name VARCHAR(50)) 
GO 
CREATE PROCEDURE dbo.GetPlayList (@Names NameList) 
AS 
BEGIN 
    WITH LearningCTE AS 
    ( SELECT l.* 
     FROM Learning l 
       INNER JOIN @Names 
        ON BandieName = Name 
     WHERE Status = 'Complete' 
    ) 
    SELECT * 
    FROM LearningCTE a 
    WHERE EXISTS 
      ( SELECT 1 
       FROM LearningCTE b 
       WHERE a.SongName = b.SongName 
       AND  Instrument != 'N/A' 
      ) 
END 

然後你可以使用VB代碼類似於此通過

Protected Sub btnGetPlaylist_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnGetPlaylist.Click 
     Dim conn As SqlConnection = Nothing 
     Try 
      Dim connString As String = "Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\BandDatabase.mdf;Integrated Security=True;User Instance=True" 
      conn = New SqlConnection(connString) 

      Dim NameTable As New DataTable() 
      NameTable.Columns.Add("Name", GetType(String)) 

      For Each item As ListItem In ListBoxBandies.Items 
       If item.Selected Then 
        Dim newRow As DataRow = NameTable.NewRow() 
        newRow(0) = item.Text 
        NameTable.Rows.Add(newRow) 
       End If 
      Next 

      Using cmd As SqlCommand = New SqlCommand("dbo.GetPlayList", conn) 
       cmd.Parameters.Add(New SqlParameter("@Names", NameTable)) 
       cmd.CommandType = CommandType.StoredProcedure 
       conn.Open() 
       Using dr As SqlDataReader = cmd.ExecuteReader(CommandBehavior.CloseConnection) 
        Dim dt As DataTable = New DataTable() 
        dt.Load(dr) 
        GridViewPlaylist.DataSource = dt 
        GridViewPlaylist.DataBind() 
       End Using 
      End Using 
     Finally 
      conn.Close() 
     End Try 

    End Sub 

我添加了一對夫婦的「使用對你的一些一次性的參數元素，但除此之外，我只是試圖重用您的代碼。