ASP.NET中使用数据处理插入数据注意的问题

webptr

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：


///ForExample:
<scriptlanguage="C#"runat="server">
SqlConnectionmySqlCon;
protectedvoidPage_Load(ObjectSrc,EventArgsE)
{
mySqlCon=newSqlConnection("server=localhost;uid=sa;pwd=sa;database=pubs");//初始化过程
if(!IsPostBack)
BindGrid();
}
publicvoidAddPublisher(Objectsender,EventArgsE)
{
StringmyinsertCmd="insertintopublishers(pub_id,pub_name,city,state,country)values(@pubid,@pubname,@city,@state,@country)";
SqlCommandmySqlCom=newSqlCommand(myinsertCmd,mySqlCon);//初始化命令调用
//实现配套
mySqlCom.Parameters.Add(newSqlParameter("@pubid",SqlDbType.Char,4));
mySqlCom.Parameters["@pubid"].Value=Pub_Id.Text;
mySqlCom.Parameters.Add(newSqlParameter("@pubname",SqlDbType.VarChar,40));
mySqlCom.Parameters["@pubname"].Value=Pub_Name.Text;
mySqlCom.Parameters.Add(newSqlParameter("@city",SqlDbType.VarChar,20));
mySqlCom.Parameters["@city"].Value=City.Text;
mySqlCom.Parameters.Add(newSqlParameter("@state",SqlDbType.Char,2));
mySqlCom.Parameters["@state"].Value=State.Text;
mySqlCom.Parameters.Add(newSqlParameter("@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
publicvoidBindGrid()
{
SqlDataAdaptermySqlCom=newSqlDataAdapter("select*frompublisherswherepub_idlike'99%'",mySqlCon);
DataSetmyds=newDataSet();
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：&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<asp:textboxid="Pub_Id"runat="server"/>姓名：&nbsp;&nbsp;
<asp:textboxid="Pub_Name"runat="server"/>
城市：&nbsp;
<asp:textboxid="City"runat="server"/>
<br/>
省：&nbsp;
<asp:textboxid="State"runat="server"/>
国家：&nbsp;
<asp:textboxid="Country"runat="server"/>
<br/>
<br/>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<asp:buttonText="提交"OnClick="AddPublisher"runat="server"ID="Button1"/><br/>
<spanid="Message"runat="server"/>
<br/>
<asp:DataGridid="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:


<<scriptlanguage="C#"runat="server">
protectedvoidPage_Load(ObjectSrc,EventArgsE)
{
//页面装载过程中直接使用IF语句，其实什么也不加！
if(!IsPostBack)
BindGrid();
}
publicvoidAddPublisher(Objectsender,EventArgsE)
{
stringstrprovider="server=localhost;uid=sa;pwd=sa;database=pubs";//构造初始化过程
SqlConnectionmySqlCon=newSqlConnection(strprovider);
stringmyinsertCmd="insertintopublishers(pub_id,pub_name,city,state,country)values(@pubid,@pubname,@city,@state,@country)";
SqlCommandmySqlCom=newSqlCommand(myinsertCmd,mySqlCon);//初始化过程实现
mySqlCom.Parameters.Add(newSqlParameter("@pubid",SqlDbType.Char,4));
mySqlCom.Parameters["@pubid"].Value=Pub_Id.Text;
mySqlCom.Parameters.Add(newSqlParameter("@pubname",SqlDbType.VarChar,40));
mySqlCom.Parameters["@pubname"].Value=Pub_Name.Text;
mySqlCom.Parameters.Add(newSqlParameter("@city",SqlDbType.VarChar,20));
mySqlCom.Parameters["@city"].Value=City.Text;
mySqlCom.Parameters.Add(newSqlParameter("@state",SqlDbType.Char,2));
mySqlCom.Parameters["@state"].Value=State.Text;
mySqlCom.Parameters.Add(newSqlParameter("@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();
}
publicvoidBindGrid()子函数调用时同样也要初始化DB连接
{
stringstrprovider="server=dev;uid=sa;pwd=pauperboyboy;database=pubs";
SqlConnectionmySqlCon=newSqlConnection(strprovider);
SqlDataAdaptermySqlCom=newSqlDataAdapter("select*frompublisherswherepub_idlike'99%'",mySqlCon);
DataSetmyds=newDataSet();
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：&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<asp:textboxid="Pub_Id"runat="server"/>姓名：&nbsp;&nbsp;
<asp:textboxid="Pub_Name"runat="server"/>
城市：&nbsp;
<asp:textboxid="City"runat="server"/>
<br>
省：&nbsp;
<asp:textboxid="State"runat="server"/>
国家：&nbsp;
<asp:textboxid="Country"runat="server"/>
<br>
<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<asp:buttonText="提交"OnClick="AddPublisher"runat="server"ID="Button1"/><br>
<spanid="Message"runat="server"/>
<br>
<asp:DataGridid="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！