c# - 如何使用小数？

在DataGridview中，我有Letter Grade、Minimum Letter Grade和Maximum Letter Grade（例如Letter Grade = A-、Minimum Letter Grade = 85,00和Maximum Letter Grade = 89,99）
例如，如果我将Minimum Letter Grade = 85,00更新为85,99，它会将其另存为85,00。
我如何才能像85,99那样更新它？
数据库中Letter Grade Min和Letter Grade Max的数据类型是DECIMAL(4,2)。

    public static void updateGradeRanges(string LetterGrd, double LgMin, double LgMax)
        try
        {
            string cmdText = "UPDATE grade_range SET LG_MIN='" + LgMin + "', LG_MAX='" + LgMax + "' WHERE Letter_Grade='" + LetterGrd + "';";
            MySqlCommand cmd = new MySqlCommand(cmdText, DB.Conn);
            int result = cmd.ExecuteNonQuery();

        }

我向这样的函数发送参数：

updateGradeRanges(LetterGrade,Convert.ToDouble(txtMinGrade.Text),Convert.ToDouble(txtMaxGrde.Text));
 <asp:UpdatePanel ID="UpdatePanel1" runat="server" Visible="true">
 <ContentTemplate>
     <asp:GridView ID="Grades_GridView" runat="server" BackColor="White" BorderColor="White"
         BorderStyle="Ridge" BorderWidth="2px" CellPadding="3" CellSpacing="1"
         GridLines="None" AutoGenerateColumns="False"
         DataKeyNames="Letter_Grade"
         onrowcancelingedit="Grades_GridView_RowCancelingEdit"
         onrowediting="Grades_GridView_RowEditing"
         onrowupdating="Grades_GridView_RowUpdating"
         onrowdeleting="Grades_GridView_RowDeleting">

         <Columns>
             <asp:TemplateField HeaderText="Letter Grade" SortExpression="Letter_Grade">

                 <ItemTemplate>
                     <asp:Label ID="Label1" runat="server" Text='<%# Bind("Letter_Grade") %>'></asp:Label>
                 </ItemTemplate>
             </asp:TemplateField>
             <asp:TemplateField HeaderText="Minimum Letter Grade" SortExpression="LG_MIN">
                 <EditItemTemplate>
                     <asp:TextBox ID="txtMinGrade" runat="server" Text='<%# Bind("LG_MIN") %>'></asp:TextBox>
                 </EditItemTemplate>

                 <ItemTemplate>
                     <asp:Label ID="Label2" runat="server" Text='<%# Bind("LG_MIN") %>'></asp:Label>
                 </ItemTemplate>
             </asp:TemplateField>
             <asp:TemplateField HeaderText="Maximum Letter Grade" SortExpression="LG_MAX">
                 <EditItemTemplate>
                     <asp:TextBox ID="txtMaxGrade" runat="server" Text='<%#Bind("LG_MAX") %>'></asp:TextBox>
                 </EditItemTemplate>

                 <ItemTemplate>
                     <asp:Label ID="Label3" runat="server" Text='<%# Bind("LG_MAX") %>'></asp:Label>
                 </ItemTemplate>
             </asp:TemplateField>

             <asp:TemplateField HeaderText="Edit" ShowHeader="False">
                 <EditItemTemplate>
                    <asp:LinkButton ID="LinkButtonUpdateGrade" runat="server" CommandName="Update" CausesValidation="True"><span class="link_span_small">Update</span></asp:LinkButton>&nbsp;
              <asp:LinkButton ID="LinkButtonCancelGrade" runat="server" CommandName="Cancel" CausesValidation="True"><span class="link_span_small">Cancel</span></asp:LinkButton>
                 </EditItemTemplate>

                 <ItemTemplate>
                     <asp:ImageButton ID="ImageButtonEditGrade" runat="server" CausesValidation="False"
                         CommandName="Edit" ToolTip="Edit" ImageUrl="~/Images/edit.png" />
                 </ItemTemplate>
             </asp:TemplateField>
             </Columns>


         <FooterStyle BackColor="#C6C3C6" ForeColor="Black" />
         <HeaderStyle BackColor="#4A3C8C" Font-Bold="True" ForeColor="#E7E7FF" />
         <PagerStyle BackColor="#C6C3C6" ForeColor="Black" HorizontalAlign="Right" />
         <RowStyle BackColor="#DEDFDE" ForeColor="Black" />
         <SelectedRowStyle BackColor="#9471DE" Font-Bold="True" ForeColor="White" />
         <SortedAscendingCellStyle BackColor="#F1F1F1" />
         <SortedAscendingHeaderStyle BackColor="#594B9C" />
         <SortedDescendingCellStyle BackColor="#CAC9C9" />
         <SortedDescendingHeaderStyle BackColor="#33276A" />


     </asp:GridView>
     </ContentTemplate>
 </asp:UpdatePanel>

最佳答案

从sql update语句中删除单引号。

关于c# - 如何使用小数？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/16243901/