使用 c# 在 ms 访问中更新

Question

有人可以帮我解决一下我的代码有什么问题吗？ 它是一个更新功能，在我的调试过程中它可以正常执行，但它没有更新我的数据库。 我已经在寻找这个问题的答案，但它仍然没有用。 我也尝试创建一个新数据库，希望它有问题但仍然没有效果。

private void update_Click(object sender, EventArgs e)
{
DataTable dt = new DataTable();
OleDbConnection con = new OleDbConnection();
con.ConnectionString = @"Provider = Microsoft.ACE.OLEDB.12.0; Data Source = C:\Users\sherilyn & justine\Documents\Visual Studio 2015\Projects\jollibee4\jollibee4\jollibee.accdb";
con.Open();
OleDbCommand cmd = new OleDbCommand();
cmd.Connection = con;
String id = dataGridView1.SelectedRows[0].Cells[0].Value + String.Empty;
int id1 = Int32.Parse(id);
try
{
if (database.selectedIndex == 0)
{
cmd.CommandText = "update Breakfast_Meals set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
else if (database.selectedIndex == 1)
{
cmd.CommandText = "update Burger_Sandwhich_Meals set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
else if (database.selectedIndex == 2)
{
cmd.CommandText = "update Chicken_Meals set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
else if (database.selectedIndex == 3)
{
cmd.CommandText = "update Dessert set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
else if (database.selectedIndex == 4)
{
cmd.CommandText = "update Kids_Meals set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
else if (database.selectedIndex == 5)
{
cmd.CommandText = "update RiceMeals_NoodlesMeals set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
else if (database.selectedIndex == 6)
{
cmd.CommandText = "update Side_Items set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
else if (database.selectedIndex == 7)
{
cmd.CommandText = "update Value_Meals set [Meals] = @meals, [Price] = @price, [Picture] = @picture, [Description] = @description WHERE [Item ID]=@id";
}
cmd.Parameters.AddWithValue("@id", id1);
cmd.Parameters.AddWithValue("@meals", meal.Text);
int mealPrice = Int32.Parse(price.Text);
cmd.Parameters.AddWithValue("@price", mealPrice);
cmd.Parameters.AddWithValue("@picture", savePhoto());
cmd.Parameters.AddWithValue("@description",description.Text);
DialogResult dialogResult = MessageBox.Show("Are you sure you want to change the data?","Warning", MessageBoxButtons.YesNo,MessageBoxIcon.Warning);
if (dialogResult == DialogResult.Yes)
{
cmd.ExecuteNonQuery();
con.Close();
}
else if (dialogResult == DialogResult.No)
{
con.Close();
}
OleDbDataAdapter adapter = new OleDbDataAdapter(cmd);
adapter.Fill(dt);
dataGridView1.DataSource = dt;
database_onItemSelected(sender, e);//to view dgv data for the selected index
con.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK,MessageBoxIcon.Error);
con.Close();
}
}

Answer 1

按占位符预期的正确顺序添加参数

cmd.Parameters.AddWithValue("@meals", meal.Text);
int mealPrice = Int32.Parse(price.Text);
cmd.Parameters.AddWithValue("@price", mealPrice);
cmd.Parameters.AddWithValue("@picture", savePhoto());
cmd.Parameters.AddWithValue("@description",description.Text);
cmd.Parameters.AddWithValue("@id", id1);

OleDb 不通过名称解析参数值，而是通过参数在参数集合中的位置。根据您的订单，where 子句中的 id 条件接收来自 description 参数的值。

也考虑使用 Add 而不是 AddWithValue

见：Can we stop using AddWithValue already?