c# - 如何使用十进制？

Question

在 DataGridview 中，我的字段是 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，如果我更新 Minimum Letter Grade = 85,00至 85,99它保存为 85,00 .

我怎样才能像85,99一样更新它？

Letter Grade Min 的数据类型和 Letter Grade Max是DECIMAL(4,2)在数据库中。

    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>

Answer 1

从您的 sql 更新语句中删除单引号。