Unity C# Microsoft SQL Server

I would like to connect to a Microsoft SQL Server from within C# while using Unity (2022.3.25f1). According to the C# Pocket Reference, it seems I can connect to SQL Server with the code marked with ★ below.

However, I get an error with using Microsoft.Data.SqlClient;. I resolved this by using NuGet in Visual Studio Community 2022 to install the Microsoft.Data.SqlClient package. This eliminated the error in Visual Studio.

However, when I press the play button in Unity, I get the message

All compiler errors have to be fixed before you can enter play mode

Do you have any solutions for this issue?

Are there any other general methods for using SQL Server with Unity (2022.3.25f1)?

Ultimately, I want to access a database stored on my home NAS from both iOS and Android devices.

Thank you for your help.