Tutorials ADO.NET Core Tutorial
DataSet — Complete Guide
DataSet — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ADO.NET Core Tutorial on Toolliyo Academy.
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ADO.NET Core Tutorial · Lesson 9 of 100
DataSet
Foundations → SQL & safety → Production → Projects
Foundations · 1 — Connections & CRUD · ~6 min · Module 1: ADO.NET Fundamentals
What is this?
DataSet is an in-memory cache of tables/relations — disconnected ADO.NET. Prefer readers for new APIs.
Why should you care?
Some ShopNest legacy WinForms modules still fill DataSets; know them to maintain, not to copy blindly.
See it live — copy this example
Use a .NET console or API project with SQL Server LocalDB. Run dotnet run after pasting.
var ds = new DataSet();
using var da = new SqlDataAdapter(
"SELECT Id, Total FROM Orders WHERE Status=@s", conn);
da.SelectCommand!.Parameters.Add("@s", SqlDbType.NVarChar, 20).Value = "Pending";
da.Fill(ds, "Orders");
Console.WriteLine(ds.Tables["Orders"]!.Rows.Count);What happened?
- SqlDataAdapter.Fill loads tables into RAM.
- Fine for small desktop grids; dangerous for huge APIs.
Practice next
- Fill a small Orders table.
- Read Rows[0]["Total"].
- Prefer reader for APIs.
- Add a second Fill for OrderItems.
- Clear the DataSet after use.
Remember
In-memory tables. Legacy-friendly. Avoid for big APIs.
Legacy ShopNest desktop
Old admin grid still uses DataSet.
Outcome: Team maintains it; new APIs use readers.
Interview prep for this lesson
Practice these questions aloud after reading—each links to a full structured answer.
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