如何包含非NULL文本框中的值

我有一个方法，可以从文本框中获取值并将其插入数据库。如何仅从已键入文本的文本框中解析值？

例如，如果文本框4、5和6为空，那么我不希望将它们解析为insert方法。

这是我为在数据库中插入一个答案而写的。我如何修改它以只包含那些不为空的文本框？

<div id="answerswer_wrapper">
                <div class="answerswer">
                    <h3 class="new">Answer 1</h3>
                    <asp:TextBox ID="AnswerBox1" runat="server" CssClass="form" Width="300px"></asp:TextBox>
                </div> <!-- end answer -->
                <div class="answerswer">
                    <h3 class="new">Answer 2</h3>
                    <asp:TextBox ID="AnswerBox2" runat="server" CssClass="form" Width="300px"></asp:TextBox>
                </div> <!-- end answer -->
                <div class="answerswer">
                    <h3 class="new">Answer 3</h3>
                    <asp:TextBox ID="AnswerBox3" runat="server" CssClass="form" Width="300px"></asp:TextBox>
                </div> <!-- end answer -->
                <div class="answerswer">
                    <h3 class="new">Answer 4</h3>
                    <asp:TextBox ID="AnswerBox4" runat="server" CssClass="form" Width="300px"></asp:TextBox>
                </div> <!-- end answer -->
                <div class="answerswer">
                    <h3 class="new">Answer 5</h3>
                    <asp:TextBox ID="AnswerBox5" runat="server" CssClass="form" Width="300px"></asp:TextBox>
                </div> <!-- end answer -->
                <div class="answerswer">
                    <h3 class="new">Answer 6</h3>
                    <asp:TextBox ID="AnswerBox6" runat="server" CssClass="form" Width="300px"></asp:TextBox>
                </div> <!-- end answer -->

protected void FinishQnrButton_Click(object sender, EventArgs e)
        {
            int QuestionnaireId = (int)Session["QuestionnaireID"];  
            SendData = new OsqarSQL();
            int questionId = SendData.InsertQuestions(QuestionName.Text, Int32.Parse(QuestnType.SelectedValue), QuestionnaireId);
            int answerId = SendData.InsertAnswer(AnswerBox1.Text, questionId, QuestionnaireId);
            Response.Redirect("~/buildq/Confirm_Questionnaire.aspx");
        } // End NewQNRButton_Click
        public int InsertAnswer(string AnswerTitle, int QuestionID, int QuestionnaireID)
        {
            int returnValue = 0;
            SqlCommand myCommand = new SqlCommand("NewAnswer", _productConn);
            myCommand.CommandType = CommandType.StoredProcedure;
            myCommand.Parameters.Add(new SqlParameter("@ANSWERTITLE", SqlDbType.NVarChar));
            myCommand.Parameters.Add(new SqlParameter("@QUESTION_ID", SqlDbType.Int));
            myCommand.Parameters.Add(new SqlParameter("@QUEST_ID", SqlDbType.Int));
            myCommand.Parameters.Add("@ANSWER_ID", SqlDbType.Int, 0, "ANSWER_ID");
            myCommand.Parameters["@ANSWER_ID"].Direction = ParameterDirection.Output;
            myCommand.Parameters[0].Value = AnswerTitle;
            myCommand.Parameters[1].Value = QuestionID;
            myCommand.Parameters[2].Value = QuestionnaireID;
            _productConn.Open();
            myCommand.ExecuteNonQuery();
            returnValue = (int)myCommand.Parameters["@ANSWER_ID"].Value;
            _productConn.Close();
            return returnValue;
        }

if (!string.IsNullOrEmpty(AnswerBox1.Text))
    int answerId = SendData.InsertAnswer(AnswerBox1.Text, questionId, QuestionnaireId);