Question

im创建一个程序，用户可以在其中上传歌曲，并将这些歌曲的元数据（例如其专辑或歌手）记录在关系sql数据库中。我当前的表格设置包含3个表格-Song_DB，Album_DB，Artist_DB。

SONG_DB：

CREATE TABLE [dbo].[SONGS_DB] (
[SONG_ID]          INT         IDENTITY (1, 1) NOT NULL,
[SONG_NAME]        NCHAR (100) NOT NULL,
[ARTIST_ID]        INT         NULL,
[ALBUM_ID]         INT         NULL,
[SONG_LENGTH]      TIME (0)    NOT NULL,
[SONG_PLAYLIST_ID] INT         NULL,
PRIMARY KEY CLUSTERED ([SONG_ID] ASC),
CONSTRAINT [FK_SONGS_DB_ToARTIST] FOREIGN KEY ([ARTIST_ID]) REFERENCES [dbo].[ARTIST_DB] ([ARTIST_ID]),
CONSTRAINT [FK_SONGS_DB_ToALBUM] FOREIGN KEY ([ALBUM_ID]) REFERENCES [dbo].[ALBUM_DB] ([ALBUM_ID]),
CONSTRAINT [FK_SONGS_DB_ToSONG_PLAYLIST] FOREIGN KEY ([SONG_PLAYLIST_ID]) REFERENCES [dbo].[SONG_PLAYLIST] ([SONG_PLAYLIST_ID])

Artist_DB

CREATE TABLE [dbo].[ARTIST_DB] (
    [ARTIST_ID] INT  IDENTITY (1, 1) NOT NULL,
    [SONG_ID]   INT  NULL,
    [NAME]      TEXT NULL,
    PRIMARY KEY CLUSTERED ([ARTIST_ID] ASC),
    CONSTRAINT [FK_ARTIST_DB_ToSONGS_DB] FOREIGN KEY ([SONG_ID]) REFERENCES [dbo].[SONGS_DB] ([SONG_ID])
);

相册数据库

CREATE TABLE [dbo].[ALBUM_DB] (
[ALBUM_ID] INT         IDENTITY (1, 1) NOT NULL,
[SONG_ID]  INT         NULL,
[NAME]     NCHAR (100) NULL,
PRIMARY KEY CLUSTERED ([ALBUM_ID] ASC),
CONSTRAINT [FK_ALBUM_DB_SONGS] FOREIGN KEY ([SONG_ID]) REFERENCES [dbo].[SONGS_DB] ([SONG_ID])

）;

我正在尝试在歌曲上传后将元数据收集到变量中后写入表。我的实际写作虽然有些困难，但是却在努力寻找如何填充外键表的方法。例如，使用以下代码，在Artist / album_DB中都不会填充song_ID，在Song_DB-

中也不会填充Album / artist_ID

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

                Dim SQLCmd As SqlCommand
                Dim SQLCmd2 As SqlCommand
                Dim SQLCmd3 As SqlCommand
                Dim SQLCmd4 As SqlCommand
                Dim SQLCmd5 As SqlCommand
                Dim SQLCmd_SID As SqlCommand
                Dim SQLCmd_ARID As SqlCommand
                Dim SQLCmd_ALID As SqlCommand
                Dim SQLCmd_ARID2 As SqlCommand
                Dim SQLCmd_ALID2 As SqlCommand
                Dim SID
                Dim ARID
                Dim ALID
                SQLcon.Open()
                SQLCmd = New SqlCommand("INSERT INTO SONGS_DB (SONG_NAME, SONG_LENGTH) VALUES (@SONG_NAME, @SONG_LENGTH)", SQLcon)
                SQLCmd.Parameters.AddWithValue("@SONG_NAME", Title)
                SQLCmd.Parameters.AddWithValue("@SONG_LENGTH", Duration)
                SQLCmd_SID = New SqlCommand("SELECT max(SONG_ID) FROM SONGS_DB", SQLcon)


                If SID = "" Then
                    SID += 1

                Else
                    SID = SQLCmd_SID.ExecuteScalar()
                    SID = Convert.ToInt32(SID)
                End If



                If Album IsNot "" Then
                    SQLCmd2 = New SqlCommand("INSERT INTO ALBUM_DB (NAME) VALUES (@NAME)", SQLcon)
                    SQLCmd2.Parameters.AddWithValue("@NAME", Album)
                    'SQLCmd2.Parameters.AddWithValue("@SONG_ID", SID)
                End If

                If Artist IsNot "" Then
                    SQLCmd3 = New SqlCommand("INSERT INTO ARTIST_DB (NAME) VALUES (@NAME)", SQLcon)
                    SQLCmd3.Parameters.AddWithValue("@NAME", Artist)
                    'SQLCmd3.Parameters.AddWithValue("@SONG_ID", SID)

                End If



                SQLCmd.ExecuteNonQuery()
                If Album IsNot "" Then
                    SQLCmd2.ExecuteNonQuery()
                End If
                If Artist IsNot "" Then
                    SQLCmd3.ExecuteNonQuery()
                End If

                If Artist IsNot "" Then
                    SQLCmd_ARID = New SqlCommand("SELECT max(ARTIST_ID) FROM ARTIST_DB", SQLcon)
                    If ARID = "" Then
                        ARID += 1

                    Else
                        ARID = SQLCmd_ARID.ExecuteScalar()
                        ARID = Convert.ToInt32(ARID)
                    End If
                    SQLCmd_ARID2 = New SqlCommand("UPDATE SONG_DB SET ARTIST_ID = (@ARTIST_ID) WHERE SONG_ID = (@SONG_ID)", SQLcon)
                    SQLCmd_ARID2.Parameters.AddWithValue("@ARTIST_ID", ARID)
                    SQLCmd_ARID2.Parameters.AddWithValue("@SONG_ID", SID)


                End If

                If Album IsNot "" Then
                    SQLCmd_ALID = New SqlCommand("SELECT max(ALBUM_ID) FROM ALBUM_DB", SQLcon)
                    If ALID = "" Then
                        ALID += 1

                    Else
                        ALID = SQLCmd_ARID.ExecuteScalar()
                        ALID = Convert.ToInt32(ARID)
                    End If
                    SQLCmd_ALID2 = New SqlCommand("UPDATE SONG_DB SET ARTIST_ID = (@ARTIST_ID) WHERE SONG_ID = (@SONG_ID)", SQLcon)
                    SQLCmd_ALID2.Parameters.AddWithValue("@ARTIST_ID", ARID)
                    SQLCmd_ALID2.Parameters.AddWithValue("@SONG_ID", SID)


                End If

                If Artist IsNot "" Then
                    SQLCmd_ARID2.ExecuteNonQuery()
                End If

                If Album IsNot "" Then
                    SQLCmd_ALID2.ExecuteNonQuery()
                End If
                SQLcon.Close()
            End If

任何想法我哪里出错了？预先感谢！

Answer 1

            If Album IsNot "" Then
                SQLCmd2 = New SqlCommand("INSERT INTO ALBUM_DB (NAME) VALUES (@NAME)", SQLcon)
                SQLCmd2.Parameters.AddWithValue("@NAME", Album)
                'SQLCmd2.Parameters.AddWithValue("@SONG_ID", SID)
            End If

            If Artist IsNot "" Then
                SQLCmd3 = New SqlCommand("INSERT INTO ARTIST_DB (NAME) VALUES (@NAME)", SQLcon)
                SQLCmd3.Parameters.AddWithValue("@NAME", Artist)
                'SQLCmd3.Parameters.AddWithValue("@SONG_ID", SID)

            End If

此代码的一半用引号引起来。替换为：

        If Album IsNot "" Then
            SQLCmd2 = New SqlCommand("INSERT INTO ALBUM_DB (NAME) VALUES (@NAME)", SQLcon)
            SQLCmd2.Parameters.AddWithValue("@NAME", Album)
            SQLCmd2.Parameters.AddWithValue("@SONG_ID", SID)
        End If

        If Artist IsNot "" Then
            SQLCmd3 = New SqlCommand("INSERT INTO ARTIST_DB (NAME) VALUES (@NAME)", SQLcon)
            SQLCmd3.Parameters.AddWithValue("@NAME", Artist)
            SQLCmd3.Parameters.AddWithValue("@SONG_ID", SID)

        End If

如注释中所述，以下行未向insert语句添加任何内容，因为该语句内没有@SONG_ID参数。这也可能引起问题。

SQLCmd3.Parameters.AddWithValue("@SONG_ID", SID) SQLCmd2.Parameters.AddWithValue("@SONG_ID", SID)

在SQL / Vb.net中的多个表之间填充主键/外键

1 个答案: