Question

您在从连接到本地SQL数据库的SQL语句填充DataGridViewer时遇到问题。这应该很简单，但是我不知道为什么它没有填充。

我基本上有3个表，如下所示-

SONGS_DB SONG_ID，SONG_NAME
SONG_PLAYLIST SONG_PLAYLIST_ID，SONG_ID，PLAYLIST_ID
播放列表 PLAYLIST_ID，PLAYLIST_NAME

在我的表单中，我有一个组合框连接到我的播放列表表，该菜单框允许用户选择要显示的播放列表-

 Private Sub Playlist_Control_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim con As New SqlConnection With {.ConnectionString = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\coolj\OneDrive\Documents\Loop\Loop\Songs_SQL.mdf;Integrated Security=True"}
    Dim cmd As New SqlCommand("SELECT * FROM Playlist", con)
    Dim Ada As New SqlDataAdapter(cmd)
    Dim Table As New DataTable()
    Ada.Fill(Table)

    ComboBox1.DataSource = Table
    ComboBox1.DisplayMember = "PLAYLIST_NAME"
    ComboBox1.ValueMember = "PLAYLIST_NAME"

End Sub

然后，当组合框值更改时，我的datagridviewer被触发，该操作旨在选择并显示指定播放列表中的所有歌曲，并执行以下代码-

Private Sub ComboBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedIndexChanged

    Dim con As New SqlConnection With {.ConnectionString = "Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\coolj\OneDrive\Documents\Loop\Loop\Songs_SQL.mdf;Integrated Security=True"}
    con.Open()

    Dim cmd As New SqlCommand("SELECT SONG_ID, SONG_NAME FROM SONGS_DB WHERE SONG_ID IN (SELECT SONG_ID FROM SONG_PLAYLIST WHERE PLAYLIST_ID IN (SELECT PLAYLIST_ID FROM Playlist WHERE PLAYLIST_NAME = (@NAME)))", con)
    cmd.Parameters.AddWithValue("@NAME", ComboBox1.SelectedItem.ToString())

    Dim Ada As New SqlDataAdapter(cmd)
    Dim Table As New DataTable()
    Ada.Fill(Table)

    DataGridView1.DataSource = Table
    con.Close()
End Sub

为什么不填充？网格显示“ SONG_ID”和“ SONG_NAME”的列标题，但不显示值。感谢所有帮助。

DataGridViewer没有从嵌套SQL填充到哪里查询？

0 个答案: