关于一个类与类之间变更传递值的问题
public void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)//下拉列表事件读取值
{
string order_byid;
if (this.DropDownList1.Text == "")
{
order_byid = "791000";//下拉列表为空,赋值791000
}
else
{
order_byid = this.DropDownList1.SelectedValue;//下拉列表不为空,赋下拉列表值
}
}
public void Button1_Click(object sender, EventArgs e)
{
if (this.r2.Checked == false && this.r1.Checked == false)
{
this.Label2.Text = "请选择机构类型";
this.Label2.Visible = true;
}
else if (this.order_id.Text == "")
{
this.Label2.Text = "请填入机构号";
this.Label2.Visible = true;
}
else if (this.order_name.Text == "")
{
this.Label2.Text = "请填入机构名称";
this.Label2.Visible = true;
}
else
{
string order_id = this.order_id.Text;
string order_name = this.order_name.Text;
string order_flag;
string conn = ConfigurationManager.AppSettings["strconn"];
OdbcConnection myconn = new OdbcConnection(conn);
myconn.Open();
string sql_add = "select * from orders where order_id='"+order_id+"'OR order_name='"+order_name+"'";
OdbcCommand myadd = new OdbcCommand(sql_add, myconn);
OdbcDataReader myaddread = myadd.ExecuteReader();
if (myaddread.HasRows)
{
this.Label2.Text = "有重复的机构号或机构名称";
this.Label2.Visible = true;
myaddread.Close();
myconn.Close();
}
else
{
DataSet ds = new DataSet();
OdbcDataAdapter da = new OdbcDataAdapter(sql_add, myconn);
OdbcCommandBuilder builder = new OdbcCommandBuilder(da);
da.Fill(ds,"orders");
DataRow tempr = ds.Tables["orders"].NewRow();
tempr["order_id"] =order_id;
tempr["order_name"] = order_name;
ds.Tables["orders"].Rows.Add(tempr);
da.Update(ds,"orders");
da.Dispose();
myaddread.Close(); //能正常运行
string sql="select * from orders where order_id='"+order_byid+"'";//这里读取的order_byid值是空值
OdbcCommand my=new OdbcCommand(sql,myconn);
OdbcDataReader myread=my.ExecuteReader();
order_byid = myread["order_byid"].ToString();//报错myread读取不存在此列/行
order_byname = myread["order_byname"].ToString();
string sql_update="update orders set order_byid='"+order_byid+"',order_byname='"+order_byname+"'where order_id='"+order_id+"'";
OdbcCommand myopen = new OdbcCommand(sql_update, myconn);
myopen.ExecuteNonQuery();
}
}
}

------解决方案--------------------

是不是order_byid要放在类里面，而不是作为方法的局部变量?

C# code

string order_byid;      //<---public void  DropDownList1_SelectedIndexChanged(object sender, EventArgs e)//下拉列表事件读取值     {              //string order_byid;                 if (this.DropDownList1.Text == "")                 {                   order_byid = "791000";//下拉列表为空,赋值791000                 }                 else                 {                    order_byid = this.DropDownList1.SelectedValue;//下拉列表不为空,赋下拉列表值                 }      }
[解决办法]
C# code
public void  DropDownList1_SelectedIndexChanged(object sender, EventArgs e)//下拉列表事件读取值     {             [color=#FF0000] string order_byid; [/color]  //这儿不用定义，order_byid应该是个全局变量，如果是bs程序，可以用viewstate["order_byid"]                if (this.DropDownList1.Text == "")                 {                   order_byid = "791000";//下拉列表为空,赋值791000                 }                 else                 {                    order_byid = this.DropDownList1.SelectedValue;//下拉列表不为空,赋下拉列表值                 }      }
[解决办法]
asp.net?你把order_byid放到Session里就可以了
C# code
public void  DropDownList1_SelectedIndexChanged(object sender, EventArgs e)//下拉列表事件读取值     {              string order_byid = "";                 if (this.DropDownList1.Text == "")                 {                   order_byid = "791000";//下拉列表为空,赋值791000                 }                 else                 {                    order_byid = this.DropDownList1.SelectedValue;//下拉列表不为空,赋下拉列表值                 }              Session["order_byid"]=order_byid;     } public void Button1_Click(object sender, EventArgs e)     {         if (this.r2.Checked == false && this.r1.Checked == false)         {             this.Label2.Text = "请选择机构类型";             this.Label2.Visible = true;         }         else if (this.order_id.Text == "")         {             this.Label2.Text = "请填入机构号";             this.Label2.Visible = true;         }         else if (this.order_name.Text == "")         {             this.Label2.Text = "请填入机构名称";             this.Label2.Visible = true;         }         else         {              string order_id = this.order_id.Text;             string order_name = this.order_name.Text;             string order_flag;             string conn = ConfigurationManager.AppSettings["strconn"];             OdbcConnection myconn = new OdbcConnection(conn);             myconn.Open();             string sql_add = "select * from orders where order_id='"+order_id+"'OR order_name='"+order_name+"'";             OdbcCommand myadd = new OdbcCommand(sql_add, myconn);             OdbcDataReader myaddread = myadd.ExecuteReader();             if (myaddread.HasRows)             {                 this.Label2.Text = "有重复的机构号或机构名称";                 this.Label2.Visible = true;                 myaddread.Close();                 myconn.Close();             }             else             {                    DataSet ds = new DataSet();                 OdbcDataAdapter da = new OdbcDataAdapter(sql_add, myconn);                 OdbcCommandBuilder builder = new OdbcCommandBuilder(da);                      da.Fill(ds,"orders");                      DataRow tempr = ds.Tables["orders"].NewRow();                      tempr["order_id"] =order_id;                      tempr["order_name"] = order_name;                      ds.Tables["orders"].Rows.Add(tempr);                      da.Update(ds,"orders");                      da.Dispose();                      myaddread.Close(); //能正常运行                       string  sql="select * from orders where order_id='"+Session["order_byid"]+"'";//这里读取的order_byid值是空值                 OdbcCommand my=new OdbcCommand(sql,myconn);                 OdbcDataReader myread=my.ExecuteReader();                 order_byid = myread["order_byid"].ToString();//报错myread读取不存在此列/行                 order_byname = myread["order_byname"].ToString();                 string sql_update="update orders set order_byid='"+order_byid+"',order_byname='"+order_byname+"'where order_id='"+order_id+"'";                 OdbcCommand myopen = new OdbcCommand(sql_update, myconn);                 myopen.ExecuteNonQuery();             }         }     } 
 
[解决办法]
string sql_update="update orders set order_byid='"+order_byid+"',order_byname='"+order_byname+"'where order_id='"+order_id+"'";
这里面的order_byid也要改成Session["order_byid"]