用一條 sql 表達既好處就係令到你基本上唔駛 programming 都可以做到 report, 例如做每月訂單量, 唔想逐月抽 data, 又或者靠個 program 黎分日子,

MySQL

[geshi lang=sql]SELECT DATE_FORMAT(`date`, ‘%m’) AS D, COUNT(*) AS C FROM orders GROUP BY DATE_FORMAT(`date`, ‘%m’)
[/geshi]

Access

[geshi lang=sql]SELECT FORMAT([date], ‘MM’) AS D, COUNT(*) AS C FROM orders GROUP BY FORMAT([date], ‘MM’)
[/geshi]

應用係 ASP.NET, 就可以用 DataSource

Default.aspx 加入 DataSource

<%@ Register Assembly="NeoControlLibrary" Namespace="NeoInformatik.Web.Controls" TagPrefix="neo" %>
…
<neo:MySqlDataSource ID="DataSouce1" ConnectionString="<%$ ConnectionStrings: Default %>" runat="server" SelectCommand="SELECT DATE_FORMAT(`date`, ‘%m’) AS D, COUNT(*) AS C FROM orders GROUP BY DATE_FORMAT(`date`, ‘%m’)" >

如果你d data 有好多年, 自己執生吧, 然後再夾埋個免費 WebChartControl (本人改到可用 DataSource),

Default.aspx 加入 Chart Control

<%@ Register Assembly="WebChart" Namespace="WebChart" TagPrefix="Web" %>

…

<Web:ChartControl ID="ChartControl1" runat="server" >
<Charts>
<Web:LineChart DataYValueField="C" DataXValueField="D" DataSource="DataSource1" >
</Web:LineChart>
</Charts>
</Web:ChartControl>

結果

咁就唔駛一行 code 都可以做到個 report: