c# beginner-How to use if-statement to check textbox is empty?

Question

I'm using textbox to insert the data to the database. However I don't want to insert null or empty value to the database. How can I use if-statement to check the textbox is empty? (which means if the textbox is empty, show a dialog to required user input data)

Here is my code:

 private void submit_button_Click(object sender, EventArgs e)
        {

        string constring = "datasource=localhost;username=root;password=";
        string Query = "INSERT INTO bug.bug (Bug_ID, title, Type_of_bug, software, software_version, description, step_to_reproduction, severity, priority, symptom) values('" + this.bugid_txt.Text+"', '" + this.title_txt.Text + "','" + this.comboBox1.Text + "','" + this.software_txt.Text + "','" + this.software_version_txt.Text + "','" + this.description_txt.Text + "','" + this.step_to_reproduction_txt.Text + "','" + this.severity_combo.Text + "','" + this.priority_combo.Text + "','" + this.symptom_txt.Text + "')";

        MySqlConnection conDataBase = new MySqlConnection(constring);
        MySqlCommand cmdDataBase = new MySqlCommand(Query, conDataBase);
        MySqlDataReader myReader;
        try
        {
            conDataBase.Open();
            myReader = cmdDataBase.ExecuteReader();
            MessageBox.Show("The Bug have been reported");
            while(myReader.Read())
            {

            }
            this.Close();
        }catch(Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

Answer 1

Be ware of Sql Injection

 private void submit_button_Click(object sender, EventArgs e)
            {

     if (!string.IsNullOrEmpty(mytextBox))
    {

      MessageBox.Show("your message goes here");
       return ;
     }

        string constring = "datasource=localhost;username=root;password=";
       // insert with parameterised query 

        MySqlConnection conDataBase = new MySqlConnection(constring);
        MySqlCommand cmdDataBase = new MySqlCommand(Query, conDataBase);
        MySqlDataReader myReader;
        try
        {
            conDataBase.Open();
            myReader = cmdDataBase.ExecuteReader();
            MessageBox.Show("The Bug have been reported");
            while(myReader.Read())
            {

            }
            this.Close();
        }catch(Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }