从函数返回布尔值时遇到一些问题

Question

我正在尝试创建一个布尔返回函数，该函数将检查文本框中的值，使用表中的数据读取器检查它是否找到匹配项，然后返回一个布尔值。我一直现在使用这个功能很长时间了，它工作正常。

   public Boolean testname()
    {
        Boolean test=false;
        SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Users\noewayout\Documents\Project.mdf;Integrated Security=True;Connect Timeout=30");
        SqlCommand cmd = new SqlCommand("select CNAME from CUSTOMER", conn);
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        string cname = "";
        while (dr.Read())
        {

            cname = Convert.ToString(dr["CNAME"]);
            if (cname == textBox1.Text.ToString())
            {
                test = true;
                return test;
            }


        }
        conn.Close();
        return test;
    }
    private void button1_Click(object sender, EventArgs e)
    {
        if (textBox1.Text == "")
        { MessageBox.Show("Please type in Customer Name"); }
        else
        {
            Boolean boo = testname();
            if (boo == false)
            {
                MessageBox.Show("Invalid Customer Name");
            }
            else if (boo == true)
            {
                try
                {
                    SqlConnection conn = new SqlConnection(@"Data Source=(LocalDB)\v11.0;AttachDbFilename=C:\Users\noewayout\Documents\Project.mdf;Integrated Security=True;Connect Timeout=30");
                    SqlCommand cmd = new SqlCommand("select ONAME,PRICE,QTY from OIL_TYPE,SALEOIL,CUSTOMER where OIL_TYPE.OID=SALEOIL.OID and CUSTOMER.CID=SALEOIL.CID and CNAME='" + textBox1.Text.ToString() + "'", conn);
                    conn.Open();
                    SqlDataReader dr = cmd.ExecuteReader();
                    int qty = 0;
                    int price = 0;
                    string oname = "";
                    while (dr.Read())
                    {
                        oname = Convert.ToString(dr["ONAME"]);
                        qty = Convert.ToInt32(dr["QTY"]);
                        price = Convert.ToInt32(dr["PRICE"]);
                        int tcost = qty * price;
                        MessageBox.Show("Oil Name\t\tQuantity\tPrice\tTotal Cost\n" + oname + " \t" + qty + "\t" + price + "\t" + tcost);
                    }
                    conn.Close();
                }
                catch (SqlException) { MessageBox.Show("Error!!"); }
            }
        }
    }

但是在过去的几个小时里，我在使用这种简单的检查方法时遇到了问题。

public Boolean testname()
    {
        Boolean test = false;
        SqlConnection conn = new SqlConnection(dbsource);
        SqlCommand cmd = new SqlCommand("select Fid from Firearm", conn);
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        string tfid = "";
        while (dr.Read())
        {

            tfid = Convert.ToString(dr["Fid"]);
            if (tfid == textBox6.Text.ToString())
            {
                test = true;
                return test;
            }


        }
        conn.Close();
        return test;
    }
    private void searchbtn_Click(object sender, EventArgs e)
    {

          string  mysql = "select * from Firearm where Fid= '" + textBox6.Text + "'";

          if (textBox6.Text == "")
          { MessageBox.Show("Please fill the text field"); }
          else
          {
              Boolean boo = testname();
              if (boo == false)
              {
                  MessageBox.Show("Invalid Fid");
              }
              else if (boo == true)
              {
                  try
                  {
                      SqlConnection conn = new SqlConnection(dbsource);
                      SqlCommand cmd = new SqlCommand(mysql, conn);
                      SqlDataAdapter sda = new SqlDataAdapter(cmd);
                      DataTable dt = new DataTable();
                      sda.Fill(dt);
                      dataGridView1.AutoGenerateColumns = true;
                      dataGridView1.DataSource = dt;

                      dataGridView1.Show();
                  }
                  catch (SqlException) { MessageBox.Show("Error!!!"); }
              }
          }
    }

即使我输入了正确的 id 值，它仍然返回 false。我已经尝试了所有我知道的但仍然没有成功。任何帮助或建议都会很棒。谢谢

Answer 1

尝试如下比较

if (tfid.Trim() == textBox6.Text.Trim())