How to use DISTINCT Keyword in mySQL using VB.Net

How to use DISTINCT Keyword in mySQL using VB.Net

How to use DISTINCT Keyword in mySQL using VB.Net.

In this tutorial, you will learn how to use the DISTINCT keyword using VB.Net.

First, we are going to create a database named distincttable. Then, we will add a table.

On your XAMPP Control Panel, click your database and click the SQL category to insert this line of code to create a table with columns:

[mysql]

CREATE TABLE IF NOT EXISTS student (
`ID` int(10) NOT NULL AUTO_INCREMENT,
`Fullname` VARCHAR(255) NOT NULL,
`Address` VARCHAR(255) NOT NULL,
`Contact_No` int(255) NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

[/mysql]

Next, we are going to add values to our table. Click your student table and then click the SQL category to insert this line of code:

[mysql]

INSERT INTO `student`(`Fullname`, `Address`, `Contact_No`)
VALUES
('Ian','Hero','21312'),
('Ian','Hero','89879'),
('Jose','De la Cruz','68768'),
('Jose','De la Cruz','03244'),
('Pablo','Tingco','34234'),
('Pablo','Tingco','42343');

[/mysql]

Next, create your VB project and drag a datagridview. Take note that you need the Mysql.Data.dll to access the mySQL methods. Also, set your datagridview AutoSizeColumnsMode to “Fill”.

Add the Mysql.Data.dll to your reference to access the mySQL methods and parameters.

At your Form1 designer, double click it and add this line of code:

[vbnet]

Imports MySql.Data.MySqlClient

Public Class Form1

Dim conn As MySqlConnection
Dim cmd As MySqlCommand
Dim da As MySqlDataAdapter
Dim dt As DataTable
Dim sql As String

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Try
conn = New MySqlConnection
conn.ConnectionString = "server=localhost; userid=root; password=; database=distincttable;"
conn.Open()
sql = "SELECT * FROM student;"
cmd = New MySqlCommand(sql, conn)
da = New MySqlDataAdapter
dt = New DataTable
da.SelectCommand = cmd
da.Fill(dt)
DataGridView1.DataSource = dt
Catch ex As MySqlException
MsgBox(ex.Message)
Finally
conn.Close()
da.Dispose()
End Try
End Sub
End Class

[/vbnet]

Run your system and your expected output should be like this:

Now, as expected we have duplicate values in the Fullname and Address columns. In order to just show up at least one value representing them, we are going to use the DISTINCT keyword of mySQL.

DISTINCT is used to return only one value from duplicate values. This is helpful especially when you want to just get the list of values without duplication.

Now, we are going to change our sql string and add the DISTINCT keyword.

[vbnet]

sql = "SELECT DISTINCT Fullname, Address FROM student;"

[/vbnet]

Load again your project and you will see the results that you can only see one value from different same values.

Congratulations! You have learned today how to use DISTINCT keyword in mySQL using VB.Net.

For questions or any other concerns or thesis/capstone creation with documentation, you can contact me through the following:

E-Mail: [email protected]

Facebook: facebook.com/kirk.lavapiez

Contact No.: +639771069640

Ian Hero L. Lavapiez

BSIT Graduate

System Analyst and Developer

Related topic(s) that you may like:

• Limiting Data Selection Query in mySQL
• Populate Multiple Data to ListView from mySQL database using VB.Net

Technology stack and requirements

To run this VB.NET project, you need the following on your development machine:

• Visual Studio 2019 or later. The free Community Edition is enough for building, debugging, and running the project.
• .NET Framework 4.7.2 or higher. Most Windows 10 and 11 systems have it preinstalled through Windows Update.
• MySQL Server 8.0 or MSSQL Express 2019. Choose whichever your capstone panel prefers; both work with VB.NET data adapters.
• MySQL Connector/NET or SqlClient library. Add via NuGet Package Manager inside Visual Studio.
• Crystal Reports (optional). Required only if the project generates printable reports; install the runtime redistributable.

Installing the source code

The download link contains a ZIP archive with the full solution. Extract and set up in five steps:

1. Extract the archive to a folder outside Program Files (avoids permission issues).
2. Open the .sln file in Visual Studio. It loads the full solution with all forms and modules.
3. Restore NuGet packages. Right-click the solution then Restore NuGet Packages if prompted.
4. Import the database. Locate the .sql file in the archive and import via phpMyAdmin (MySQL) or SQL Server Management Studio.
5. Update the connection string in App.config or module code to match your local database name, user, and password.

How to use this project for your BSIT capstone

This VB.NET project maps cleanly to standard BSIT capstone documentation. Suggested chapter alignment:

• Chapter 1 (Introduction). Discuss the problem the system solves in real-world context. Cite Philippine business or academic use cases where a manual process could be replaced.
• Chapter 2 (Review of Related Literature). Compare this system’s features against 5-10 similar published projects. Cite journals like IJERT or IEEE Access for academic-standard sources.
• Chapter 3 (Methodology). Include Use Case Diagram, Data Flow Diagram, Entity Relationship Diagram, and Activity Diagram covering all major workflows in the system.
• Chapter 4 (Results and Discussion). Screenshot each module of the running system with a caption explaining what data it processes and which user role interacts with it.
• Chapter 5 (Conclusion and Recommendations). Identify features that could be added in a Version 2, such as web dashboard, mobile app, or REST API export.

Modules typical of How to use DISTINCT Keyword in mySQL using VB.Net

• Master data. CRUD forms for the primary entities the system manages, with search and filter.
• Transaction processing. Data entry forms for the day-to-day operations the system automates.
• Reports. Formatted printable output summarizing activity per day, per user, or per category.
• User management. Login with role-based permissions (Admin, Encoder, Viewer).
• Backup and restore. Export database to a .sql or .bak file and restore when needed.

Common enhancements for capstone review

• Modernize the UI. Add Bunifu or Guna UI controls for a more polished, modern appearance.
• Add printable receipts. Integrate a printer preview form with page-setup options.
• Multi-user concurrency. Ensure the database handles simultaneous writes without lost-update errors.
• Web version. Rewrite the front-end in ASP.NET Core or React for a modern deployment path.