Simplify Data Entry User Experience with AutoComplete

A tutorial demonstrating the power of AutoComplete feature of the TextBox control using Windows Forms client and SQL Server 2000 data.

A tutorial demonstrating the power of AutoComplete feature of the TextBox control using Windows Forms client and SQL Server 2000 data.



Figure: 1 - Example in run-time mode




If you ask any end-user, what is that most desired feature they look for in software application? I bet the most common answer is, "must be easy to use". There're many different ways one can improve the end-user experience. In this article I'll demonstrate you how a simple AutoComplete feature of TextBox control can greatly enhance the Data Entry.


I assume the reader has the basic understanding of the Visual Studio 2005 IDE and comfortable with writing the code using C#. Since this tutorial is using data stored inside SQL Server, basic understanding of SQL statement and data connectivity is desirable.


What is AutoComplete?


It is always a good thing to learn with the help of an example; Internet Explorer includes a feature called AutoComplete that keeps track of information that you've recently typed, such as Web site addresses, information in forms, and search queries. As you type new information, AutoComplete tries to anticipate what you are typing and offers possible matches. You save time because you don't have to type in the full information-just select AutoComplete's match and go!


Say you've recently visited the Web site and you want to go back. You can type "http://www.eb" or even just "eb" and AutoComplete will fill in the rest of the Web address for you. If you've visited more than one place on a Web site, AutoComplete will present you with a list of places you've been on that site.


Well, good it works with Internet Explorer. However, I wanted to see the same can be done with my Accounting Application. If I type data inside Customer ID TextBox, will I be able to see list of all the Customers in the system?


Sure you can, with the help of new functionality built into TextBox control; developer can design application which can have AutoComplete feature. Here is the deal, if you want to be treated like super hero by your end-users? Then you go ahead put this feature in your application and enjoy the fame (trust me on this, I already have three promissory notes of parties from one of my overseas client, imagine if one don't need to remember 2000+ customer ids anymore).


Let's create a Windows Application Project 

If VS 2005 IDE is not already started, then you can launch the IDE by clicking on windows Start button --> All programs --> Microsoft Visual Studio 2005 --> click on icon Microsoft Visual Studio 2005. You may have others ways to lunch the IDE, such as clicking it on your desktop and so on.

Please do the following steps to create a Windows Application Project:

  • Click on menu File --> New --> Project... or you can press the hot key Ctrl + Shift + N (please see Figure 2)
  • From New Project dialog box select --> Visual C# --> Windows
  • From Templates select --> Windows Application 
  • Please give the name to the application; I've called the project as "WinAutoComplete". You may choose a different location for storing the application files as per your preference. Please see Figure 3 for illustration of the naming process.
  • Click on OK button to finish the process. VS 2005 will create a new project and more or less your project should look like Figure 4.


Figure: 2 - Process to create New Windows Application Project



Figure: 3 - Project selection and naming process



Figure: 4 - View of newly created project

As such, most of you'll see something similar to what the Figure 4 looks like; however, depends on your current VS 2005 IDE settings, you might see some toolbox hidden or floating. In any case, you should see the blank Form1 created for you as a result of new project. Please refer to VS2005 help to customize the look and feel of IDE.

Tip: You can always access the menu View --> Toolbox or press Ctrl + Alt + X, to make Toolbox window visible if it is hidden or you don't see it in IDE. To get the maximum space on designer surface, you may like to use Auto Hide feature of Toolboxes.

Let's set properties of Form1 as per Table 1, to make sure the look and feel is good enough for our end-users to provide input (if any) and view the report. In case if property tool box is not visible in IDE, you may hit F4 key to make it visible. Pease make sure to select Form1 by before applying changes to properties using property toolbox.

Table 1. Properties of Form1




Windows Forms AutoComplete Example


375, 200

Note: When a new project is created, a solution is also gets created with it. You may have one or more project inside one solution.


Time to add some controls to newly created Form1


This is how the example looks like: I'll create a sample application which let user type the Product Id from NorthWind Database of SQL Server 2000. AutoComplete works in different pattern; I'll make sure user try different pattern and see which one works better for them.


We need the following controls on Form1:   

  • ComboBox with different pattern of AutoComplete
  • Three Labels (Pattern Type, Product ID and File System)
  • Two TextBoxs (Product ID and File System) 

Let's start by dragging and dropping above mentioned controls on the Form1. Please make sure your Form1 looks like something similar to Figure 5.



Figure: 5 - Form1 designer surface after adding controls


Please change the properties of controls as per Table 2:

Table 2. Properties setup of controls on Form1

Report Item





Pattern Type



Product ID



File System















Let's write some C# code to bring life to Form1


Bulk of the code is written inside Load event of Form1. The instruction to define which Pattern must be applied is written inside selected index change event of comboBoxPatten. Please make sure you code looks like as follows:

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.Data.SqlClient;

using System.Collections;


namespace WinAutoComplete


    public partial class Form1 : Form


        AutoCompleteStringCollection ProductList = new



        public Form1()





        private void Form1_Load(object sender, EventArgs e)


            //declare connection string

            string cnString = @"Data Source=(local); Initial Catalog=northwind;" +

            "User Id=northwind;Password=northwind";


            /*use following if you use standard security

            string cnString = @"Data Source=(local);Initial

            Catalog=northwind; Integrated Security=SSPI"; */


            //declare Connection, command and other related objects

            SqlConnection conGetData = new SqlConnection(cnString);

            SqlCommand cmdGetData = new SqlCommand();

            SqlDataReader drGetData;




                //open connection



                //prepare connection object to get the data through

                //reader and populate into dataset

                cmdGetData.CommandType = CommandType.Text;

                cmdGetData.Connection = conGetData;

                cmdGetData.CommandText = "Select ProductName From Products";


                //read data from command object

                drGetData = cmdGetData.ExecuteReader();


                if (drGetData.HasRows == true)


                    while (drGetData.Read())




                    MessageBox.Show("No data found in Products tables");


                //close reader and connection




                //set the default pattern to SuggestAppend

                comboBoxPattern.SelectedIndex = 2;

                txtProductID.AutoCompleteMode = AutoCompleteMode.SuggestAppend;

                txtProductID.AutoCompleteSource = AutoCompleteSource.CustomSource;

                txtProductID.AutoCompleteCustomSource = ProductList;


            catch (Exception ex)






                //check if connection is still open then attempt to close it

                if (conGetData.State == ConnectionState.Open)







        private void comboBoxPattern_SelectedIndexChanged(object sender, EventArgs e)


            switch (comboBoxPattern.Text)


                case "Suggest":

                    txtProductID.AutoCompleteMode = AutoCompleteMode.Suggest;


                case "Append":

                    txtProductID.AutoCompleteMode = AutoCompleteMode.Append;


                case "SuggestAppend":

                    txtProductID.AutoCompleteMode = AutoCompleteMode.SuggestAppend;







Let the show begin!


Hurry! We're done with all the hard work, its time to reap the fruit. Let's build the project and see if your project looks some what same as shown in Figure 1. So, fingers crossed? And ready to hit F5 on your keyboard?


I assume at this moment that your code has no compile level error which will prevent the build to happen. Now, go ahead and check how the result looks like. To me, I can only imagine two typical scenarios; either you'll be throwing your hands in the air and yell YES, or a Silent whisper, Ops.


In both the cases I'm with you. If you said YES, then congratulation, you've done it. This is just the beginning, soon you'll find yourself cracking heck of cool AutoComplete enabled data entry controls. Now, if you've said Ops, then nothing to panic, just simply make sure you have done all the steps. In case of major issue, just start from scratch.




If we use this pattern of AutoComplete then end-user will see the suggested entry appended as each key is pressed. For example if you type: "to" you will get "tofu". See Figure 6 for example of Append pattern.



Figure: 6 - Example of Append Pattern




If we use this pattern of AutoComplete then end-user will see the suggested entry is displayed with narrowed down choices as each key is pressed. However, the product ID field will not be appended. For example if you type: "to" you will not get "tofu" appended to Product ID textbox. See Figure 7 for example of Suggest pattern.



Figure: 7 - Example of Suggest Pattern




SuggestAppend pattern is combination of both Suggest and Append. Please see Figure 1 for the example of this pattern.




As you can see, a simple feature like this can go a long way to win trust of your end-users and improve user experience. Apart from providing custom source, you can see that in build AutoComplete features like File System is also handy to help the data entry done easily.


Thank you for reading; I sincerely hope this article will help you a bit or two to know about user interface enhancement. Feel free to drop me a line with your comments/suggestion at