COM Interop

Populate Dropdown List From Database In Classic ASP (Vbscript)

In this article we will be discussing a simple way to populate a dropdown list control in a Classic ASP web page. This tutorial is for beginners who have just started going through the legacy applications written in VBScript/Jscript for Classic ASP. This is also useful for people interested in COM Interop.
 
We will be using  VBscript to code the Classic ASP page. The same objective can be achieved using JScript but with a different syntax.
 
Let's start with the steps.

Step 1

When the page is loaded for the first time we will be checking the already saved value in the database so that it can be displayed as the selected text in the dropdown.

Please refer to the code snippet below. I have used Product_id as a querystring parameter to search the database. Also I have declared a function to set the selected text of dropdown.
  1. <%    
  2.     'Get the value of parameter from querystring   
  3.     Product_ID = Request.Querystring("ProductID")  
  4.   
  5.     'Declare a variable to store the connection string  
  6.     Dim connstr  
  7.     connstr = "Provide your connection string"  
  8.   
  9.     'Create a new ADODB recordset    
  10.     set rsSelectedProduct = Server.CreateObject("ADODB.recordset")   
  11.   
  12.     'Create a new ADODB connection   
  13.     Set conn = Server.CreateObject("ADODB.Connection")   
  14.   
  15.     'Open the connection using the connection string    
  16.     conn.open connstr  
  17.   
  18.     'Store  the query in a variable , in real world scenario we should be using a stored procedure with parameters  
  19.     QuerySQL = "Select  Product_name from tbl_Products where Product_ID = '" & Product_ID & "'"   
  20.   
  21.     'Execute the query   
  22.     set rsSelectedProduct = conn.Execute(QuerySQL)    
  23.   
  24.     'Check if recordset is empty , if not then store the value   
  25.     if not rsSelectedProduct.EOF then    
  26.       product = rsSelectedProduct("Product_name")    
  27.     else    
  28.       product = ""    
  29.     end if  
  30.        
  31.     'Close the Connection and recordset  
  32.   
  33.     rsSelectedProduct.Close  
  34.     conn.Close  
  35.     Set rsSelectedProduct = Nothing  
  36.     Set conn = Nothing 

  37.     'Declare a function to set the selected text   
  38.     Function selectProduct(vProduct)    
  39.       if vProduct = product then    
  40.           Response.Write("selected=""selected""")         
  41.      end if    
  42.     End Function  

  44.     %> 
Step 2

Inside the server side vbscript code Create a new ADODB connection, ADODB Recordset and open the connection using the required connection string.

Please refer to the code snippet below.
  1. <%    
  2.  'Create Connection object  
  3. Set conn2 = Server.CreateObject("ADODB.Connection")    
  4. 'Create Recordset object  
  5. Set rsProductList = Server.CreateObject("ADODB.recordset")  
  6.   
  7. 'Open the connection using the previous connection string
  8. conn2.open connstr    
  9.   
  10. 'Declare a variable to store the query to be excuted. Here we are using a hardcoded query.We can also use a stored procedure  
  11.  QueryProduct = "select Product_Name,Product_ID from tbl_Products order by Product_Name asc" 
  12. %>
Step 3

Execute the query and populate the Recordset from the result. Then convert the recordset to a 2 dimensional array in Vbscript.

Refer to the code below.
  1. <%    
  2. 'Execute the query   
  3. set rsProductList = conn2.Execute(QueryProduct)    
  4. 'Declare the array  
  5. Dim arrProducts   
  6.     
  7. if not rsProductList.EOF then    
  8.     arrProducts = rsProductList.GetRows()  ' Convert recordset to 2D Array  
  9. end if   
  10. 'Close the Connection and recordset  
  11.   
  12. rsProductList.Close  
  13. conn2.Close  
  14. Set rsProductList = Nothing  
  15. Set conn2 = Nothing  
  16.   
  17. %>   
Step 4

Create the dropdown list tag inside the HTML <body> section of the page. Here I have used the 2D Array generated in step 3 above.
  1. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">  
  2. <html xmlns="http://www.w3.org/1999/xhtml">  
  3. <head>  
  4. <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />  
  5. <title>Populate Product dropdown</title>  
  6. </head>  
  7. <body>  
  8. <br/>  
  9. <label id="lblOne" for="ddlproduct" title="Select Product:" class="Example">Product:</label>  
  10. <select name="productSelect" id="productSelect">  
  11.   <%  
  12.       'Check whether it's a proper array or not  
  13.         if IsArray(arrProducts) then  
  14.   
  15.             For i = 0 to ubound(arrProducts, 2) %>  
  16.   
  17.             <option value="<%= arrProducts(1,i)%>" <%= selectProduct(arrProducts(0,i)) %>> <%= arrProducts(0,i) %> </option>  
  18.   
  19.            <% next %>  
  20.   
  21.         <% else %>  
  22.   
  23.             <option value=""> Select </option>  
  24.   
  25.         <% end if %>  
  26.   
  27.        </select>  
  28. </body>  
  29. </html>   
Here is the Complete code for the page test.asp. If we host this page in IIS then we will be able to see the dropdown generated. 
  1. <%      
  2.     'Get the value of parameter from querystring     
  3.     Product_ID = Request.Querystring("ProductID")    
  4.     
  5.     'Declare a variable to store the connection string    
  6.     Dim connstr    
  7.     connstr = "Provide your connection string"    
  8.     
  9.     'Create a new ADODB recordset      
  10.     set rsSelectedProduct = Server.CreateObject("ADODB.recordset")     
  11.     
  12.     'Create a new ADODB connection     
  13.     Set conn = Server.CreateObject("ADODB.Connection")     
  14.     
  15.     'Open the connection using the connection string      
  16.     conn.open connstr    
  17.     
  18.     'Store  the query in a variable , in real world scenario we should be using a stored procedure with parameters    
  19.     QuerySQL = "Select  Product_name from tbl_Products where Product_ID = '" & Product_ID & "'"     
  20.     
  21.     'Execute the query     
  22.     set rsSelectedProduct = conn.Execute(QuerySQL)      
  23.     
  24.     'Check if recordset is empty , if not then store the value     
  25.     if not rsSelectedProduct.EOF then      
  26.       product = rsSelectedProduct("Product_name")      
  27.     else      
  28.       product = ""      
  29.     end if    
  30.          
  31.     'Close the Connection and recordset    
  32.     
  33.     rsSelectedProduct.Close    
  34.     conn.Close    
  35.     Set rsSelectedProduct = Nothing    
  36.     Set conn = Nothing   
  37.   
  38.     'Declare a function to set the selected text     
  39.     Function selectProduct(vProduct)      
  40.       if vProduct = product then      
  41.           Response.Write("selected=""selected""")           
  42.      end if      
  43.     End Function    
  44.   
  45.     'Create Connection object    
  46.     Set conn2 = Server.CreateObject("ADODB.Connection")      
  47.     'Create Recordset object    
  48.     Set rsProductList = Server.CreateObject("ADODB.recordset")    
  49.     
  50.     'Open the connection using the previous connection string  
  51.     conn2.open connstr      
  52.     
  53.      'Declare a variable to store the query to be excuted. Here we are using a hardcoded query.We can also use a stored procedure    
  54.     QueryProduct = "select Product_Name,Product_ID from tbl_Products order by Product_Name asc"    
  55.   
  56.      'Execute the query   
  57.     set rsProductList = conn2.Execute(QueryProduct)    
  58.      'Declare the array  
  59.     Dim arrProducts   
  60.     
  61.     if not rsProductList.EOF then    
  62.           arrProducts = rsProductList.GetRows()  ' Convert recordset to 2D Array  
  63.     end if   
  64.       
  65.    'Close the Connection and recordset    
  66.     
  67.     rsProductList.Close    
  68.     conn2.Close    
  69.     Set rsProductList = Nothing    
  70.     Set conn2 = Nothing   
  71. %>    
  72.   
  73. <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">    
  74. <html xmlns="http://www.w3.org/1999/xhtml">    
  75. <head>    
  76. <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />    
  77. <title>Populate Product dropdown</title>    
  78. </head>    
  79. <body>    
  80. <br/>    
  81. <label id="lblOne" for="ddlproduct" title="Select Product:" class="Example">Product:</label>    
  82. <select name="productSelect" id="productSelect">    
  83.   <%    
  84.       'Check whether it's a proper array or not    
  85.         if IsArray(arrProducts) then    
  86.     
  87.             For i = 0 to ubound(arrProducts, 2) %>    
  88.     
  89.             <option value="<%= arrProducts(1,i)%>" <%= selectProduct(arrProducts(0,i)) %>> <%= arrProducts(0,i) %> </option>    
  90.     
  91.            <% next %>    
  92.     
  93.         <% else %>    
  94.     
  95.             <option value=""> Select </option>    
  96.     
  97.         <% end if %>    
  98.     
  99.        </select>    
  100. </body>    
  101. </html>   
I hope this will be useful for beginners who have just started going through legacy ASP code. Comments and feedback are always welcome.Thank you.
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