处理从数据库到 GridView 的 NULL [英] Handling NULL from database to GridView
问题描述
我有一个简单的 GridView,可以直接从数据库中显示一些值.在数据库中有一个名为 MaxNoPlaces 的列.该列表示 ID 为 ObjectValue 的 TextBox 的最大长度.问题是有时数据库中的值为 NULL,当我运行应用程序绑定失败并且无法加载页面时.如何在数据库中管理 null 并将它们在 maxlenght 中转换为 0 到该文本框?
I have a simple GridView that show some values directy from database. In database there's a column named MaxNoPlaces. That column represents maxlenght of TextBox with id ObjectValue. The problem is sometimes the value in the database is NULL and when I run the app binding fails and page cannot be loaded. How can I manage null in database and convert them to 0 in maxlenght to that textbox ?
提前致谢!
<asp:GridView ID="gvMyObjects" runat="server" CellPadding="4" ForeColor="#333333" GridLines="None" CssClass="GridView" AutoPostBack="False" AutoGenerateColumns="False" >
<AlternatingRowStyle BackColor="White" />
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:UpdatePanel ID="UpdatePanel2" runat="server">
<ContentTemplate>
<button class="myBtn" id="Button1" type="button" data-toggle="modal" data-target="#myModal" runat="server" ><span>Select</span></button>
</ContentTemplate>
</asp:UpdatePanel>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="ID" >
<ItemTemplate>
<asp:Label ID="ObjectID" runat="server" margin-Left="100px" Text='<%# Bind("ObjekatID") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Name">
<ItemTemplate>
<asp:Label ID="ObjectName" runat="server" margin-Left="100px" Text='<%# Bind("ObjectName") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Value">
<ItemTemplate>
<asp:TextBox ID="ObjectValue" runat="server" margin-Left="100px" MaxLength='<%# Bind("MaxNoPlaces") %>' Text='<%# Bind("ObjectValue") %>'></asp:TextBox>
</ItemTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText="Value">
<ItemTemplate>
<asp:Label ID="Object" runat="server" margin-Left="100px" Text='<%# Bind("Object") %>'></asp:Label>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
推荐答案
只要你检索数据就可以在 sql 查询中简单地写
You can simply do it in sql query whenever you retrieving data just write
select ISNULL(MaxNoPlaces,0) as MaxNoPlaces FROM table_Name
因此如果数据库具有NULL值,它将返回0.
so it will return 0 if database having NULL value.
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