C# 向 DataGridView 插入和更新内容不起作用！答案

【问题标题】：C# Insert and Update content to DataGridView do not work !C# 向 DataGridView 插入和更新内容不起作用！
【发布时间】：2011-06-07 12:15:31
【问题描述】：

我在这里遇到了一个非常麻烦的问题，查询似乎显然是正确的，但它没有返回任何数据行...

基本上问题是在插入之后，我进行选择以获取变量的自动增量编号（NAlbum）（我正在使用 C#），这是困扰我的一段代码

            //Associar ID de Artista
            ClassBD.DBMyReader(
                "SELECT NArtista " +
                "FROM Artistas " +
                "WHERE (Nome = '" + CBBoxAddArtista.Text + "')");
            ClassBD.myReader.Read();
            temptabelas[0] = ClassBD.myReader.GetInt32(0);

            //Associar ID da Editora
            ClassBD.DBMyReader(
                "SELECT NEditora " +
                "FROM Editora " +
                "WHERE (Nome = '" + CBBoxAddEditora.Text + "')");
            ClassBD.myReader.Read();
            temptabelas[1] = ClassBD.myReader.GetInt32(0);

            //Associar ID da Media
            ClassBD.DBMyReader(
                "SELECT NMedia " +
                "FROM Media " +
                "WHERE (Nome = '" + CBBoxAddMedia.Text + "')");
            ClassBD.myReader.Read();
            temptabelas[2] = ClassBD.myReader.GetInt32(0);

            //Associar ID do Genero
            ClassBD.DBMyReader(
                "SELECT NGenero " +
                "FROM Genero_de_Musica " +
                "WHERE (Nome = '" + CBBoxAddGenero.Text + "')");
            ClassBD.myReader.Read();
            temptabelas[3] = ClassBD.myReader.GetInt32(0);

            ClassBD.DBMyInsertCommand("INSERT INTO Albuns " +
                "(NArtista, NEditora, NGeneroDeMusica, NMedia, Nome, [Ano de Edição])" +
                "VALUES (" + temptabelas[0] + "," + temptabelas[1] + "," + temptabelas[2] + "," + temptabelas[3] + ",'" + TxtAddMusicaAlbum.Text + "'," + int.Parse(TxtAddAnoEdicao.Text) + ")");

            ClassBD.DBMyReader("SELECT MAX(NAlbum) AS Actual " +
                               "FROM Albuns");
            tempnalbum = ClassBD.myReader.GetInt32(0);

            musicasBindingSource.Filter = "NAlbum = " + tempnalbum;

提前致谢，路易斯·达科斯塔

【问题讨论】：

使用参数化查询。
你有 5 次选择和 1 次插入，那一次是不返回任何数据行的？
您好，1)“使用参数化查询”？ - 你能详细说明一下吗，我对 SQL 不是很熟悉......：S...... 2）不返回任何数据行的是这个：ClassBD.DBMyReader（“SELECT MAX（NAlbum）AS Actual” + "来自阿尔本斯");

标签： c# mysql datagridview rows

【解决方案1】：

第一。您需要参数化查询以获得更简洁的语法。

例子：

string CommandText = "select NArista from Artista where Nome=@Nome";
cmd = new SqlCommand(CommandText);
cmd.Connection = con;
cmd.Parameters.AddWithValue("@Nome",CBBoxAddArtista.Text);  
rdr = cmd.ExecuteReader();  
while(rdr.Read())
{
 temptabelas[0] = rdr["NAtista"].ToString()                      
}

在将结果加载到 Data gridview 之后，循环所有值然后使用您的插入语句。

例子：

foreach (DataGridViewRow dr in Datagridview1.Rows)
{
//Do your Code
"INSERT INTO Albuns " +
 "(NArtista, NEditora, NGeneroDeMusica, NMedia, Nome, [Ano de Edição])" +
"VALUES (@1,@2,@3,@4,@5,@6)";
// Add parameter
cmd.Parameters.AddWithValue("@1",(string) dr.Cells["Natista"].Value.ToString()); 
.
.
.
.
cmd.Parameters.AddWithValue("@6",int.Parse(TxtAddAnoEdicao.Text)


cmd.ExecuteNonQuery();

 }

【讨论】：

【解决方案2】：

大家好，

ClassBD.DBMyInsertCommand("INSERT INTO Albuns " +
                "(NArtista, NEditora, NGeneroDeMusica, NMedia, Nome, [Ano de Edição]) " +
                "VALUES (" + temptabelas[0] + "," + temptabelas[1] + "," + temptabelas[2] + "," + temptabelas[3] + ",'" + TxtAddMusicaAlbum.Text + "'," + int.Parse(TxtAddAnoEdicao.Text) + ")");

            OleDbConnection connection = new OleDbConnection(ClassBD.MyConnectionString);
            connection.Open();
            OleDbCommand MyCommand = new OleDbCommand("SELECT NAlbum FROM Albuns WHERE (Nome = @Nome)", connection);
            MyCommand.Parameters.AddWithValue("@Nome", TxtAddMusicaAlbum.Text);
            OleDbDataReader myReader = MyCommand.ExecuteReader(CommandBehavior.CloseConnection);
            ClassBD.tempnalbum = myReader.GetInt32 ;

“嗨，我昨天问了这个问题，你让我参数化查询，所以我做了......但是，它仍然没有行......帮助？” "（插入是正确的，我已经检查了它的条目）

【讨论】：

您有一个插入命令，但您甚至不使用执行非查询来执行它。 command("INSERT") command.executenonquery();

【解决方案3】：

Private Sub BoundLoadButton_Click(ByVal sender As System.Object, 
                                  ByVal e As System.EventArgs) 
                                  Handles BoundLoadButton.Click
     swatch.Reset()
     swatch.Start()
     Cursor = Cursors.WaitCursor
     Try
        Using BoundObject As New UnboundClass(mMySQLConnectionString)
           Call BoundObject.BoundDataLoading(UnboundDataGridView, _
                                             RecordCountTextBox, _
                                             mErrorMsgString)
           If Not IsNothing(mErrorMsgString) Then
              Cursor = Cursors.Default
              MessageBox.Show(mErrorMsgString, _
                              Me.Text, _
                              MessageBoxButtons.OK, _
                              MessageBoxIcon.Error)
           End If
        End Using
     Catch exError As Exception
        MessageBox.Show(exError.Message, _
                        Me.Text, _
                        MessageBoxButtons.OK, _
                        MessageBoxIcon.Error)
     End Try
     Cursor = Cursors.Default
     swatch.Stop()
     mTimeDouble = swatch.ElapsedMilliseconds * 0.001
     BoundTimeTextBox.Text = mTimeDouble.ToString
End Sub

【讨论】：