在 2 个表单之间发送数据
我有带有 datagridview 和一个按钮的 form1。当我单击一个按钮时，会打开一个新表单，其中有一个文本框和一个按钮。在这个文本框中，我可以编写查询，并单击一个按钮，查询结果显示在 form1 datagridview 中。问题是它打开了 form1 的另一个实例，但我希望 form1 始终保持打开状态，并且根据 form2 中的查询输入，只有 datagridview 中的记录在发生变化。form1 和 form2 都需要在调用时打开并处于活动状态。
这是我的代码：
//FORM 1
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
var queryForm = new Form2();
queryForm.Show(this);
}
//FORM 2
public Form2()
{
InitializeComponent();
}
private SqlConnection Conn;
private void Form1_Load(object sender, EventArgs e)
{
Conn = new SqlConnection(@"Data Source=srvr;Initial Catalog =db; User ID =user; Password =pass");
}
private void btnExecute_Click(object sender, EventArgs e)
{
Form1 frm1 = new Form1();
frm1.Show(this);
frm1.Activate();
SqlCommand cmd = new SqlCommand();
cmd.Connection = Conn;
cmd.CommandText = txtQuery.Text;
try
{
Conn.Open();
SqlDataReader reader = cmd.ExecuteReader();
frm1.dataGridView1.Columns.Clear();
frm1.dataGridView1.Rows.Clear();
if (reader.HasRows)
{
DataTable schema = reader.GetSchemaTable();
int field_num = 0;
foreach (DataRow schema_row in schema.Rows)
{
int col_num = frm1.dataGridView1.Columns.Add(
"col" + field_num.ToString(),
schema_row.Field<string>("ColumnName"));
field_num++;
frm1.dataGridView1.Columns[col_num].AutoSizeMode =
DataGridViewAutoSizeColumnMode.AllCells;
}
object[] values = new object[reader.FieldCount];
while (reader.Read())
{
reader.GetValues(values);
frm1.dataGridView1.Rows.Add(values);
}
}
}
catch (Exception ex)
{
MessageBox.Show("Error executing command.\n" + ex.Message);
}
finally
{
Conn.Close();
}
}
翻阅古今2回答
-
桃花长相依
好吧，既然你在打电话Form1 frm1 = new Form1();- 你还期待opens up another instance of form1什么？- 为什么不应该new Form1()产生另一个实例？您将需要获取已创建的Form1.例如，请参见 在 c# windows 应用程序中查找打开的表单当你找到它时，你可以激活它，例如：var frm1 = Application.OpenForms[0];//frm1.Show(this); <- don't need to call Show since its already openfrm1.Activate();你也应该改变你btnExecute_Click的。private void btnExecute_Click(object sender, EventArgs e){ var frm1 = Application.OpenForms[0] as Form1; //find `Form1` like you want, I only take [0] //always create a new instance of SqlConnection here and dispose it with the using Keyword //don't use a private field to try to keep the Connection, let the internal Connection pool handle that case using (var con = new SqlConnection(@"Data Source=srvr;Initial Catalog =db; User ID =user; Password =pass")) { try { con.Open(); //clean up, Command/Reader with using keyword using (var cmd = con.CreateCommand()) { cmd.CommandText = txtQuery.Text; using (SqlDataReader reader = cmd.ExecuteReader()) { //read data } } } catch (Exception ex) { MessageBox.Show("Error executing command.\n" + ex.Message); } } //should activate the `Form1` AFTER the job is done, you can consider if you only want to activate it if the previous Code didn't fail frm1.Activate();}不要真正了解您在“read_data”例程中所做的事情。此代码块：frm1.dataGridView1.Columns.Clear();frm1.dataGridView1.Rows.Clear();if (reader.HasRows){ DataTable schema = reader.GetSchemaTable(); int field_num = 0; foreach (DataRow schema_row in schema.Rows) { int col_num = frm1.dataGridView1.Columns.Add( "col" + field_num.ToString(), schema_row.Field<string>("ColumnName")); field_num++; frm1.dataGridView1.Columns[col_num].AutoSizeMode = DataGridViewAutoSizeColumnMode.AllCells; } object[] values = new object[reader.FieldCount]; while (reader.Read()) { reader.GetValues(values); frm1.dataGridView1.Rows.Add(values); }}尝试以下是否足够，将上面代码中的我的注释“//读取数据”替换为：frm1.dataGridView1.AutoGenerateColumns = true; //say to automatically create columns, based on the result inside the datatablefrm1.dataGridView1.Columns.Clear();var dataTable = new DataTable();dataTable.Load(dataReader); //load the SqlDataReader into the DataTablefrm1.dataGridView1.DataSource = dataTable; //set the dataGridView's DataSource to the dataTable -
陪伴而非守候
在 form1 中单击按钮时，您可以简单地打开 form2 的一个新实例并在那里完成您的工作，并在关闭时在 form1 中接收该值。或者您可以通过构造函数将 form1 的实例传递到 form2 并从 form2 更新 form1。例如：var isFormClosed = false;using(form1 frm = new form1()){ // do something here frm.ShowDialog(); isFormClosed = true;}或者，如果您希望将 form1 的引用传递给 form2，var isFormClosed = false;using(form1 frm = new form1(this)){ // do something here frm.ShowDialog(); isFormClosed = true;}在这里，在 form2 中，您可以简单地使用 form1 的传递引用来更新属性或网格。
随时随地看视频慕课网APP
相关分类
C#