我正在尝试通过点击按钮(btnsearch_Click)访问主表单中的事件,每次我点击它,它都会显示“对象引用未设置为对象实例”。
以下是我的代码:
用户控件
namespace Purchase_Order
{
public partial class Search : UserControl
{
public event EventHandler btnSearchClicked;
public Search()
{
InitializeComponent();
}
private void btnsearch_Click(object sender, EventArgs e)
{
btnSearchClicked(sender, e);
}
}
}
主要表格
namespace Purchase_Order
{
public partial class formMain : Form
{
public formMain()
{
InitializeComponent();
}
private void formMain_Load(object sender, EventArgs e)
{
Search searchbox = new Search();
searchbox.btnSearchClicked += new EventHandler(SearchClicked);
}
void SearchClicked(object sender, EventArgs e)
{
MySqlConnection con = new MySqlConnection(serverstring);
try
{
string query = "SELECT * FROM tblclassification WHERE INSTR(class_name, @search)";
MySqlCommand cmd = new MySqlCommand(query, con);
MySqlDataAdapter da = new MySqlDataAdapter(cmd);
Search content = new Search();
cmd.Parameters.AddWithValue("@search", content.btnsearch.Text);
DataTable dt = new DataTable();
da.Fill(dt);
classification control = new classification();
control.dataGridView1.DataSource = dt;
control.dataGridView1.DataMember = dt.TableName;
panelMain.Controls.Clear();
panelMain.Controls.Add(control);
MessageBox.Show("OK");
}
catch (Exception)
{
throw;
}
finally
{
if (con.State == ConnectionState.Open)
{
con.Close();
}
}
}
serverstring
变量在哪里初始化了? - Ant P