Question

如何存储查询结果以获取位置，以便我可以在另一个私有void方法中使用它？我试图用作会话，但我无法让它工作。 C＃总是强调它的某些部分是红色的。任何想法都会有所帮助。以下是我如何从数据库中提取信息。

private void LoginButton_Click(object sender, EventArgs e)
    {

 string commandText = "SELECT RIGHTS FROM [USER] WHERE Username=@p1 and [Password]=@p2";
     using (OleDbCommand command = new OleDbCommand(commandText, con))
     {
       command.Parameters.AddWithValue("@p1", textBox1.Text);
       command.Parameters.AddWithValue("@p2", textBox2.Text);
       string query = (string)command.ExecuteScalar();
       {

         if (query == "Manager")
         {
          string locationText = "SELECT LOCATION FROM [USER] WHERE Username=@p1 and [Password]=@p2";
          using (OleDbCommand location = new OleDbCommand(locationText, con))
          {
            location.Parameters.AddWithValue("@p1", textBox1.Text);
            location.Parameters.AddWithValue("@p2", textBox2.Text);
            string locationResult = (string)command.ExecuteScalar();
            {

            }
       }
     }
  }

然后我想在相同的Windows窗体中使用它，以便它只显示用户所在的位置。

private void groupBox5_Enter(object sender, EventArgs e)
    {
        //Load Employee Name
        using (OleDbConnection con = new OleDbConnection(constring))
        {
            try
            {
                string query = "SELECT TellerNum FROM EMPLOYEE WHERE Location = locationResult ORDER BY TellerNum ASC";
                OleDbDataAdapter da = new OleDbDataAdapter(query, con);
                con.Open();
                DataSet ds = new DataSet();
                da.Fill(ds, "Name");
                comboBox14.DisplayMember = "TellerNum";
                comboBox14.DataSource = ds.Tables["Name"];
                con.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }

我不确定如何调用第一个查询的结果并将其放在第二个查询中。我把＆＃34; locationResult＆＃34;在查询中所以我记得那是我需要它去的地方。如果您有任何想法，我很乐意听到。

Answer 1

您可以将第一个查询的结果存储在类字段中。只需创建：

private string LocationFromQuery;

您班级中的

字段，并为其指定值。

Answer 2

在页面级别的string locationResult函数之外声明LoginButton_Click。

说private string locationResult

然后设置此变量值

private void LoginButton_Click(object sender, EventArgs e)
{
 //.... all your code

  locationResult = (string)command.ExecuteScalar();
}

然后在你的第二个函数下，在sql查询中使用该变量值

private void groupBox5_Enter(object sender, EventArgs e)
{
 //.... all your code

 string query = "SELECT TellerNum FROM EMPLOYEE WHERE Location ='" + locationResult + "' ORDER BY TellerNum ASC";

 //...all your code

}

Answer 3

也许你应该使用全局变量。

private string Location="";

private void LoginButton_Click(object sender, EventArgs e)
    {

 string commandText = "SELECT RIGHTS FROM [USER] WHERE Username=@p1 and [Password]=@p2";
     using (OleDbCommand command = new OleDbCommand(commandText, con))
     {
       command.Parameters.AddWithValue("@p1", textBox1.Text);
       command.Parameters.AddWithValue("@p2", textBox2.Text);
       string query = (string)command.ExecuteScalar();
       {

         if (query == "Manager")
         {
          string locationText = "SELECT LOCATION FROM [USER] WHERE Username=@p1 and [Password]=@p2";
          using (OleDbCommand location = new OleDbCommand(locationText, con))
          {
            location.Parameters.AddWithValue("@p1", textBox1.Text);
            location.Parameters.AddWithValue("@p2", textBox2.Text);
            string Location = (string)command.ExecuteScalar();
            {

            }
       }
     }
  }

 private void groupBox5_Enter(object sender, EventArgs e)
{
   if(!Location.Equals("")){
    //Load Employee Name
    using (OleDbConnection con = new OleDbConnection(constring))
    {
        try
        {
            string query = "SELECT TellerNum FROM EMPLOYEE WHERE Location = @p1 ORDER     BY TellerNum ASC";
            location.Parameters.AddWithValue("@p1", Location);
            OleDbDataAdapter da = new OleDbDataAdapter(query, con);
            con.Open();
            DataSet ds = new DataSet();
            da.Fill(ds, "Name");
            comboBox14.DisplayMember = "TellerNum";
            comboBox14.DataSource = ds.Tables["Name"];
            con.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
      }
    }
}

我没有尝试过这段代码，但是你需要做的就是让它工作。

但我认为将数据库处理代码放到gui上并不算太幸运。你应该阅读MVC和MVP。

在另一个私有void方法中使用查询结果

3 个答案: