Posted 14 December 2022, 6:22 pm EST
As mentioned in the comments above, the .net 4 framework includes System.Data.SqlClient, you only need to add a reference to your project.
From this document, you can know that the minimum version of the .net framework that Microsoft.Data.SqlClient depends on is .NETFramework 4.6.1.
For changing the version when downloading the package, you can select other versions in the Version drop-down box.
)System.Data.SqlClient was part of the runtime in .NET 4.0 and even .NET 1.0, when there was no NuGet, so the question is unclear. Why not just add using System.Data.SqlClient;? There’s no code that actually demonstrates a problem, not even an error message 2) .NET 4.0 is out of support for several years. And won’t even be available in any machine unless you target Windows XP. In all others, installing a newer runtime like 4.5 would replace 4.0. 4.x runtimes are binary replacements.