我正在使用以下代碼在 accessdb 中搜索輸入的文本框 ID，并將資料行回傳到 dataGridView。當我搜索第二個 ID 時，GridView 中的第一行被替換，我怎樣才能讓它保存多行？
該專案的最終目標是允許用戶搜索任意數量的 ID，并將相應的資料行拉入 gridview，然后將所有資料保存到 csv 中。
private void searchButton_Click(object sender, EventArgs e)
{
conn1.Open();
//return ID, IMEI, TekNum, BatchNum, ICCID, IMSI from dataBase
OleDbCommand cmd1 = new OleDbCommand("Select ID, IMEI, TekNum, BatchNum, ICCID, IMSI from TBLTest1 where ID=@param1", conn1);
cmd1.Parameters.AddWithValue("@param1", txtScannedValue.Text);
OleDbDataReader reader1;
reader1 = cmd1.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(reader1);
//dataGridView1.DataSource= dt;
if (dt.Rows.Count > 0)
{
((DataTable)dataGridView1.DataSource).ImportRow(dt.Rows[0]);
}
else
{
MessageBox.Show("No Data Found");
}
//reset textBox
txtScannedValue.Text = "";
conn1.Close();
}
uj5u.com熱心網友回復：
您正在做的是 - 每次按下searchButton_Click按鈕時，您正在運行一個僅回傳 1 行的查詢（ID=@param1），然后您將所有（由于查詢，在您的情況下始終為 1）您搜索的行插入到您的dataGridView通過.DataSource()系結。為了解決這個問題，我建議您重新實作資料系結：
我假設這DataTable是從ADO.NET所以不改變查詢你可以系結你的資料是這樣的：
// this is pseudocode
private void searchButton_Click(object sender, EventArgs e) {
var row = (DataGridViewRow) dataGridView1.Rows[0].Clone();
var retrievedRow = getRowById(txtScannedValue.Text);
if (retrievedRow is null) return;
row.Cells[0].Value = retrievedRow.value1; // bind here you model fields
row.Cells[1].Value = retrievedRow.value2;
// ...
dataGridView1.Rows.Add(row);
}
private void getRowById(string id) {
conn1.Open();
OleDbCommand cmd1 = new OleDbCommand("Select ID, IMEI, TekNum, BatchNum, ICCID, IMSI from TBLTest1 where ID=@param1", conn1);
cmd1.Parameters.AddWithValue("@param1", id);
OleDbDataReader reader1;
reader1 = cmd1.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(reader1);
DataRow row;
if (dt.Rows.Count > 0) {
row = dt.Rows[0];
}
conn1.Close();
return row;
}
uj5u.com熱心網友回復：
我會使用 ListBox 或 ComboBox 來呈現他們可以通過可用的 id 識別的資料。要追加行，請使用 DataTable.ImportRow。
這里使用一個 ComboBox 來呈現，在這種情況下是員工，并且 DataGridView 最初填充了一個空的 DataTable。
單擊按鈕以獲取要附加到 DataGridView 的基礎 DataTable 的行。
模型和資料操作
using System.Collections.Generic;
using System.Data;
using System.Data.OleDb;
namespace AccessApplication.Classes
{
public class EmployeesOperations
{
public static string ConnectionString =>
"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=NorthWind.accdb";
public static List<Employee> EmployeesList()
{
List<Employee> list = new List<Employee>();
using var cn = new OleDbConnection { ConnectionString = ConnectionString };
using var cmd = new OleDbCommand() { Connection = cn };
cmd.CommandText = "SELECT EmployeeID, FirstName, LastName FROM Employees";
cn.Open();
var reader = cmd.ExecuteReader();
while (reader.Read())
{
list.Add(new Employee()
{
Id = reader.GetInt32(0),
FirstName = reader.GetString(1),
LastName = reader.GetString(2)
});
}
return list;
}
public static DataTable EmptyDataTable()
{
using var cn = new OleDbConnection { ConnectionString = ConnectionString };
using var cmd = new OleDbCommand() { Connection = cn };
cmd.CommandText =
"SELECT TOP 1 EmployeeID, FirstName, LastName FROM Employees";
cn.Open();
DataTable table = new DataTable();
table.Load(cmd.ExecuteReader());
table.Rows.Clear();
return table;
}
public static DataTable SingleRow(int identifier)
{
using var cn = new OleDbConnection { ConnectionString = ConnectionString };
using var cmd = new OleDbCommand() { Connection = cn };
cmd.CommandText =
"SELECT TOP 1 EmployeeID, FirstName, LastName "
"FROM Employees WHERE EmployeeID = @Id";
cmd.Parameters.Add("@Id", OleDbType.Integer).Value = identifier;
cn.Open();
DataTable table = new DataTable();
table.Load(cmd.ExecuteReader());
return table;
}
}
public class Employee
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public override string ToString() => $"{FirstName} {LastName}";
}
}
表格代碼
public partial class EmployeeForm : Form
{
private readonly BindingSource _employeesBindingSource =
new BindingSource();
public EmployeeForm()
{
InitializeComponent();
_employeesBindingSource.DataSource = EmployeesOperations.EmployeesList();
EmployeesComboBox.DataSource = _employeesBindingSource;
dataGridView1.DataSource = EmployeesOperations.EmptyDataTable();
}
private void GetSingleEmployeeButton_Click(object sender, EventArgs e)
{
int id = ((Employee)EmployeesComboBox.SelectedItem).Id;
DataTable table = ((DataTable)dataGridView1.DataSource);
DataRow result = table.AsEnumerable()
.FirstOrDefault(row => row.Field<int>("EmployeeID") == id);
// only add if not already in the data grid view
if (result == null)
{
table.ImportRow(EmployeesOperations.SingleRow(id).Rows[0]);
}
}
}
uj5u.com熱心網友回復：
下面的代碼現在用于使用文本框搜索資料庫并在 dataGridView 中輸入多行代碼。這個問題在 JohnG 對 op 的評論中得到了回答。在這里張貼以供將來參考。
private void searchButton_Click(object sender, EventArgs e)
{
conn1.Open();
//return ID, IMEI, BatchNum, ICCID, IMSI from dataBase
OleDbCommand cmd1 = new OleDbCommand("Select ID, IMEI, BatchNum, ICCID, IMSI from TBLTest1 where ID=@param1", conn1);
cmd1.Parameters.AddWithValue("@param1", txtScannedValue.Text);
OleDbDataReader reader1;
reader1 = cmd1.ExecuteReader();
DataTable dt = new DataTable();
dt.Load(reader1);
if (dt.Rows.Count > 0)
{
if (dataGridView1.DataSource != null) {
((DataTable)dataGridView1.DataSource).ImportRow(dt.Rows[0]);
}
else
{
dataGridView1.DataSource = dt;
}
}
else
{
MessageBox.Show("No Data Found");
}
//reset textBox
txtScannedValue.Text = "";
conn1.Close();
}
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