ASP.NET中使用數據處理插入數據注意的問題

2024-07-10 13:04:28

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很多時候，我們都會習慣將數據庫連接的初始化過程交給page_load去做，其實這樣子有好處也有壞處，好處是單邊問題的時候，這種方法很實用，壞處就是遇到多邊的問題時，就種情況這不太好用了！例如下面的例子：

/// for example:

<script language="c#" runat="server">
sqlconnection mysqlcon;
protected void page_load(object src,eventargs e)
{
mysqlcon=new sqlconnection("server=localhost;uid=sa;pwd=sa;database=pubs"); //初始化過程
if (!ispostback)
bindgrid();
}
public void addpublisher(object sender, eventargs e)
{
string myinsertcmd = "insert into publishers ( pub_id, pub_name, city, state, country ) values (@pubid,@pubname,@city,@state,@country)";
sqlcommand mysqlcom = new sqlcommand(myinsertcmd, mysqlcon);  //初始化命令調用
//實現配套
mysqlcom.parameters.add(new sqlparameter("@pubid", sqldbtype.char, 4));
mysqlcom.parameters["@pubid"].value = pub_id.text;
mysqlcom.parameters.add(new sqlparameter("@pubname", sqldbtype.varchar, 40));
mysqlcom.parameters["@pubname"].value = pub_name.text;
mysqlcom.parameters.add(new sqlparameter("@city", sqldbtype.varchar, 20));
mysqlcom.parameters["@city"].value = city.text;
mysqlcom.parameters.add(new sqlparameter("@state", sqldbtype.char, 2));
mysqlcom.parameters["@state"].value = state.text;
mysqlcom.parameters.add(new sqlparameter("@country",sqldbtype.varchar, 30));
mysqlcom.parameters["@country"].value = country.text;
//打開db
mysqlcom.connection.open();
mysqlcom.executenonquery();
message.innerhtml = "<b>已添加記錄</b><br/>";
mysqlcom.connection.close();
pub_id.text = "";
pub_name.text = "";
city.text= "";
state.text = "";
country.text = "";
bindgrid();
}
//子函數調用
public void bindgrid()
{
sqldataadapter mysqlcom = new sqldataadapter("select * from publishers where pub_id like '99%'", mysqlcon);
dataset myds = new dataset();
mysqlcom.fill(myds, "publishers");
dgmygrid.datasource = myds.tables["publishers"].defaultview; dgmygrid.databind();
}
</script>
<h2>添加一個新的發行者：</h2>
<br/>
發行者 id 應以 99 打頭，并包含 4 位數字<br/>
發行者 id：        
<asp:textbox id="pub_id" runat="server" />姓名：  
<asp:textbox id="pub_name" runat="server" />
城市： 
<asp:textbox id="city" runat="server" />
<br/>
省： 
<asp:textbox id="state" runat="server" />
國家： 
<asp:textbox id="country" runat="server" />
<br/>
<br/>
           
<asp:button text="提交" onclick="addpublisher" runat="server" id="button1" /><br/>
<span id="message" runat="server" />
<br/>
<asp:datagrid id="dgmygrid" runat="server" />

這樣的例子初初看起來沒有問題，調試也沒報錯，但在生成的頁面添加數據后提交時就會報錯，說什么屬性不配套之類的話。是什么原因造成的呢！其實，這就是初始化過程在頁面裝載時造成的，但這里有個問題我始終沒能搞清楚，就是既然是在頁面初始化過程已經初始化過db實例了，按道理來講應該可以直接生成套用的啊，但好像沒有！還是要把初始化過程放到具體的函數里面才能實現！看下面:
<<script language="c#" runat="server">

   protected void page_load(object src,eventargs e)
   {
   //頁面裝載過程中直接使用if語句，其實什么也不加！
   if (!ispostback)
   bindgrid();
   }
   public void addpublisher(object sender, eventargs e)
    {
   string strprovider="server=localhost;uid=sa;pwd=sa;database=pubs"; //構造初始化過程
   sqlconnection mysqlcon=new sqlconnection(strprovider);
   string myinsertcmd ="insert into publishers ( pub_id, pub_name, city, state, country ) values (@pubid,@pubname,@city,@state,@country)";
   sqlcommand mysqlcom = new sqlcommand(myinsertcmd,mysqlcon);   //初始化過程實現
   mysqlcom.parameters.add(new sqlparameter("@pubid", sqldbtype.char, 4));
   mysqlcom.parameters["@pubid"].value = pub_id.text;
   mysqlcom.parameters.add(new sqlparameter("@pubname", sqldbtype.varchar, 40));
   mysqlcom.parameters["@pubname"].value = pub_name.text;
   mysqlcom.parameters.add(new sqlparameter("@city", sqldbtype.varchar, 20));
   mysqlcom.parameters["@city"].value = city.text;
   mysqlcom.parameters.add(new sqlparameter("@state", sqldbtype.char, 2));
   mysqlcom.parameters["@state"].value = state.text;
   mysqlcom.parameters.add(new sqlparameter("@country",sqldbtype.varchar, 30));
   mysqlcom.parameters["@country"].value = country.text;
   mysqlcom.connection.open();
   mysqlcom.executenonquery();
   message.innerhtml = "<b>已添加記錄</b><br>";
   mysqlcom.connection.close();
   pub_id.text = "";
   pub_name.text = "";
   city.text= "";
   state.text = "";
   country.text = "";
   bindgrid();
   }
    public void bindgrid()  子函數調用時同樣也要初始化db連接
    {
    string strprovider="server=dev;uid=sa;pwd=pauperboyboy;database=pubs";
    sqlconnection mysqlcon=new sqlconnection(strprovider);
    sqldataadapter mysqlcom = new sqldataadapter("select * from publishers where pub_id like '99%'",mysqlcon);
    dataset myds = new dataset();
    mysqlcom.fill(myds, "publishers");
    dgmygrid.datasource = myds.tables["publishers"].defaultview;
    dgmygrid.databind();
    }
   </script>
   <h2>添加一個新的發行者：</h2>
   <br>
   發行者 id 應以 99 打頭，并包含 4 位數字<br>
   發行者 id：        
   <asp:textbox id="pub_id" runat="server" />姓名：  
   <asp:textbox id="pub_name" runat="server" />
   城市： 
   <asp:textbox id="city" runat="server" />
   <br>
   省： 
   <asp:textbox id="state" runat="server" />
   國家： 
   <asp:textbox id="country" runat="server" />
   <br>
   <br>
              
   <asp:button text="提交" onclick="addpublisher" runat="server" id="button1" /><br>
   <span id="message" runat="server" />
   <br>
   <asp:datagrid id="dgmygrid" runat="server" />
  </form>>

經過這樣修改后，我們才能在真正意義上實現數據的增加！但我也試了數據的刪除和更新，在頁面裝載時直接賦于其初始化db屬性卻沒有問題，不知道是什么原因，知道的人給提個醒哦！謝謝 :)