如何使用下拉列表从数据库获取显示的值? [英] How to get displayed values from database using dropdownlist?

问题描述

我创建了一个包含2个dropdownmenu(dpmtList amd empList)的表单
通过数据库访问项目.一个下拉菜单包含部门列表(来自数据库)，另一个下拉菜单是选定部门的雇员列表，

我曾经使用过嵌套的if else语句，而且总是得到else语句中的员工列表...
编码如下

创建了两个功能
loademploeelist()
loaddepartmentlist()

I have created one form containing 2 dropdownmenu(dpmtList amd empList)
accessing items through database.One dropmenu contains list of department (from database) and other dropmenu is list of employees of specified department which is selected

i have used nested if else statement and always i get list of employees which are in else statement...
coding is below

created two functions
loademploeelist()
loaddepartmentlist()

protected void Page_Load(object sender, EventArgs e)
    {
        
            loademploeelist();
           loaddepartmentlist();
        
    }
 protected void loaddepartmentlist()
    {
        SqlConnection CON;
        SqlCommand COM;
        SqlDataReader READER;

        string ConnectionString = ConfigurationManager.ConnectionStrings["EMP"].ConnectionString;
        CON = new SqlConnection(ConnectionString);
        COM = new SqlCommand("Select department from dpmt", CON);

        try
        {
            CON.Open();
            READER = COM.ExecuteReader();
            dpmtList.DataSource = READER;
            dpmtList.DataValueField = "department";
            dpmtList.DataBind();
            READER.Close();
            
        }

        catch
        {
            CON.Close();
        }
      
    }
 protected void loademploeelist();
    {
                   SqlConnection CON;
                        SqlCommand COM;
            
            SqlDataReader READER;

            string ConnectionString = ConfigurationManager.ConnectionStrings["EMP"].ConnectionString;
            CON = new SqlConnection(ConnectionString);

            if (dpmtList.Text == "Administrartor")
            {
                COM = new SqlCommand("Select Name,ID from AD",CON);
            }

            else if (dpmtList.Text == "hr")
            {
                COM = new SqlCommand("Select Name,ID from Her", CON);
               
            }
            else if (dpmtList.Text == "IT")
            {
               COM = new SqlCommand("Select Name,ID from IT", CON);


            }
            else 
            {
            COM = new SqlCommand("Select Name,ID from HD",CON);

            }
           
            
            CON.Open();
            READER = COM.ExecuteReader();
            empList.DataSource = READER;
            empList.DataValueField = "ID";
            empList.DataTextField = "Name";
            empList.DataBind();

            READER.Close();

            CON.Close();

        }
    }

在这里administerartor，HR IT，HD are department

请告诉我但我的错误并纠正它
问候，

here administerartor,HR IT ,HD are department

Pls do tell me abut my mistake and rectify it
regards,

推荐答案

我建​​议不要为相同的信息使用单独的表.用一个列创建一个表，该列指示该记录所属的部门.这将使数据库更具扩展性，并使您的代码更容易.可以使用简单的级联模式填充下拉列表.

I would suggest not using separate tables for the same information. Create one table with a column that indicates what department the record belongs to. It will make the database more extensible and your code much easier. The dropdowns could be populated with a simple cascading pattern.

在选定索引中调用此loademploeelist()函数
的已更改事件 您的部门下拉菜单

取选择的值/文本作为您的要求
并根据该值/文本绑定您的员工下拉菜单

还可以使Department的下拉列表autopostback属性= true;/xml>

Call this loademploeelist() function in selected index Changed event of
your Department dropdown

take that selected value/text whichever is your Requirement
and on the basis of that value/text bind your employee dropdown

also Make Department dropdown autopostback property = true;/xml>

处理选定的下拉列表更改事件并调用您的方法

并在pageload上检查pagepostback

handle selectedidexchange events for dropdown and call your methods

and check pagepostback on pageload

protected void Page_Load(object sender, EventArgs e)
   {
       if (!IsPostBack)
       {
           loademploeelist();
           loaddepartmentlist();
       }
   }

这篇关于如何使用下拉列表从数据库获取显示的值?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！