ASP.NET中使用数据处理插入数据注意的问题

2024-07-10 13:04:28

字体：大中小

来源：转载

供稿：网友

很多时候，我们都会习惯将数据库连接的初始化过程交给page_load去做，其实这样子有好处也有坏处，好处是单边问题的时候，这种方法很实用，坏处就是遇到多边的问题时，就种情况这不太好用了！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"); //初始化过程
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);  //初始化命令调用
//实现配套
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;
//打开db
mysqlcom.connection.open();
mysqlcom.executenonquery();
message.innerhtml = "<b>已添加记录</b><br/>";
mysqlcom.connection.close();
pub_id.text = "";
pub_name.text = "";
city.text= "";
state.text = "";
country.text = "";
bindgrid();
}
//子函数调用
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>添加一个新的发行者：</h2>
<br/>
发行者 id 应以 99 打头，并包含 4 位数字<br/>
发行者 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" />
国家： 
<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" />

这样的例子初初看起来没有问题，调试也没报错，但在生成的页面添加数据后提交时就会报错，说什么属性不配套之类的话。是什么原因造成的呢！其实，这就是初始化过程在页面装载时造成的，但这里有个问题我始终没能搞清楚，就是既然是在页面初始化过程已经初始化过db实例了，按道理来讲应该可以直接生成套用的啊，但好像没有！还是要把初始化过程放到具体的函数里面才能实现！看下面:
<<script language="c#" runat="server">

   protected void page_load(object src,eventargs e)
   {
   //页面装载过程中直接使用if语句，其实什么也不加！
   if (!ispostback)
   bindgrid();
   }
   public void addpublisher(object sender, eventargs e)
    {
   string strprovider="server=localhost;uid=sa;pwd=sa;database=pubs"; //构造初始化过程
   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);   //初始化过程实现
   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>已添加记录</b><br>";
   mysqlcom.connection.close();
   pub_id.text = "";
   pub_name.text = "";
   city.text= "";
   state.text = "";
   country.text = "";
   bindgrid();
   }
    public void bindgrid()  子函数调用时同样也要初始化db连接
    {
    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>添加一个新的发行者：</h2>
   <br>
   发行者 id 应以 99 打头，并包含 4 位数字<br>
   发行者 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" />
   国家： 
   <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>>

经过这样修改后，我们才能在真正意义上实现数据的增加！但我也试了数据的删除和更新，在页面装载时直接赋于其初始化db属性却没有问题，不知道是什么原因，知道的人给提个醒哦！谢谢 :)