我到处都看了,但我似乎无法让它发挥作用。
我正在尝试从DataGridView更新Access数据库。将数据库加载到网格中工作正常。我使用了this site中描述的说明。
但是,要根据对DataGridView所做的更改来更新数据库,我使用了命令dataAdapter.Update(datatable);
,但是根据位置(此代码旁边),代码会运行,但数据库不会更新。如果我将它放在一个按钮中,则会在插入到语句中引发异常“语法错误”。
其他问题:我应该在加载DataGridView后关闭连接变量吗?如果是这样,我应该重新打开它来执行更新,然后重新关闭它吗?这有什么作用?。
非常感谢任何帮助。 编辑:Tim问全班,
public partial class Pantalla_Proyecto : Form
{
private Inicio Inicio;
private List<string> Logueado;
private OleDbConnection conn;
private OleDbDataAdapter Adaptador;
private DataTable Tabla;
private BindingSource Bsource;
private OleDbCommandBuilder Builder;
public Pantalla_Proyecto(Inicio Inicio, List<string> Logueado)
{
this.Inicio =Inicio;
this.Logueado = Logueado;
InitializeComponent();
}
private void Pantalla_Proyecto_Load(object sender, EventArgs e)
{
}
private void importarCDPToolStripMenuItem_Click(object sender, EventArgs e)
{
Importar_CDP Importar_CDP = new Importar_CDP();
Importar_CDP.Show();
}
private void importarListasToolStripMenuItem_Click(object sender, EventArgs e)
{
WindowsFormsApplication1.Formularios.Lista_Lazos.Importar_Listas1 Importar_Listas = new WindowsFormsApplication1.Formularios.Lista_Lazos.Importar_Listas1();
Importar_Listas.Show();
}
private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
}
private void flowLayoutPanel2_Paint(object sender, PaintEventArgs e)
{
}
private void menuStrip1_ItemClicked(object sender, ToolStripItemClickedEventArgs e)
{
}
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
string sql = "Select * From ["+TABLE (THIS IS A STRING I GET FROM PREVIOUS FORM)+"]";
conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=proyectos\" + Location(this is a string i get on the previous form) + ".mdb;User Id=admin;Password=;");
conn.Open();
// Extraemos info de mi database y la meto en un datatable
Adaptador = new OleDbDataAdapter(sql, conn);
Builder = new OleDbCommandBuilder(Adaptador);
Tabla = new DataTable();
Adaptador.Fill(Tabla);
// LLENO EL DATA GRID VIEW
Bsource = new BindingSource();
Bsource.DataSource = Tabla;
dataGridView1.DataSource = Bsource;
dataGridView1.Dock = DockStyle.Fill;
Adaptador.Update(Tabla);//if i put it here nothing happens
conn.Close();
}
private void dataGridView1_Validating(object sender, CancelEventArgs e)
{
}
private void button1_Click_1(object sender, EventArgs e)
{
conn.Open();
Adaptador.Update(Tabla);//IF i put it here i get an exception
conn.Close();
}
答案 0 :(得分:1)
根据OP的请求详细说明using语句,让我们采用comboBox1_SelectedIndexChanged方法:
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
string sql = "Select * From ["+TABLE (THIS IS A STRING I GET FROM PREVIOUS FORM)+"]";
using (conn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=proyectos\" + Location(this is a string i get on the previous form) + ".mdb;User Id=admin;Password=;"))
{
conn.Open();
// Extraemos info de mi database y la meto en un datatable
Adaptador = new OleDbDataAdapter(sql, conn);
// Remove the OleDbCommandBuilder
Tabla = new DataTable();
Adaptador.Fill(Tabla);
// LLENO EL DATA GRID VIEW
Bsource = new BindingSource();
Bsource.DataSource = Tabla;
dataGridView1.DataSource = Bsource;
dataGridView1.Dock = DockStyle.Fill;
// ** NOTE:
// At this point, there's nothing to update - all that
// has happened is that you've bound the DataTable
// to the DataGridView.
Adaptador.Update(Tabla);//if i put it here nothing happens
} // Your connection will be closed at this point when the using
// statement goes out of scope.
}
<强>更新强>
MSDN说“当你创建一个新实例OleDbCommandBuilder时,任何与这个OleDbDataAdapter相关的现有OleDbCommandBuilder都会被释放。”
但是,如果你想完全摆脱OleDbCommandBuilder,你可以这样做(我更新了上面的代码来做到这一点)。既然你认为你遇到了特殊字符的问题,那么这样做可能是值得的。
这样的事情会有所帮助 - 您必须根据表格列的内容修改更新命令:
private void button1_Click_1(object sender, EventArgs e)
{
conn.Open();
Adaptador.UpdateCommand = "<Your SQL here>" // I.e., UPDATE [TABLE] SET....
try
{
Adaptador.Update((DataTable)Bsource.DataSource);
}
catch (Exception ex)
{
// Do something with the exception
}
}
此代码是MSDN的略微修改版本:
How to: Bind Data to the Windows Forms DataGridView Control
请注意,他们在示例中使用了SqlDbCommandBuilder,但总体原则保持不变。
根据David-W-Fenton的评论,您可能希望在Form_Load事件中进行连接和dataadapter初始化,然后关闭Form_Closing事件上的连接。
答案 1 :(得分:0)
首先要检查的是您实际更新的Access文件的运行时路径。
如果您正在使用VS.NET,MDB文件是项目的一部分,并且MDB文件中的“Copy Local”选项设置为true,那么每次运行时都可能是程序覆盖上次执行的更新。
我只是提到因为我被这个人咬了一下; - )
干杯