I am trying to connect my Unity project with a SQL Server database using VS 2022, but when typing my code, I get the following error:

Error CS1069
The type name ‘SqlConnection’ could not be found in the namespace ‘System.Data.SqlClient’. This type has been forwarded to assembly ‘System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089’ Consider adding a reference to that assembly.
Assembly-CSharp C:UsersgerarUnityMSSQL_pruebaAssetsScriptsGenerateLabels.cs 21 Active

Also, since I am new to .NET, I am not sure what type is being used (.NET / .NET Core), I am not diving into it as I am only trying to use it for Unity.

This is the code I am using:

using System;
using System.Data;
using System.Data.SqlClient; // Here I use SqlClient
using UnityEngine;
using static UnityEngine.UIElements.UxmlAttributeDescription;

public class GenerateLabels : MonoBehaviour
{
    public string UserName;

    function void Start()
    {
        Debug.Log("Hello world !!!");
        string connectionString =
           "Server=XX;" + 
           "Database=XX;" + 
           "User ID=XX;" + 
           "Password=XX;"; 
        IDbConnection dbcon;
        using (dbcon = new SqlConnection(connectionString)) // This line is where the error is displayed.
        {
            dbcon.Open();

            using (IDbCommand dbcmd = dbcon.CreateCommand())
            {
                string sql = "SELECT Name, UserPrincipalName FROM Users WHERE Id=1";
                dbcmd.CommandText = sql;

                using (IDataReader reader = dbcmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        string FirstName = (string)reader["Name"];
                        string LastName = (string)reader["UserPrincipalName"];
                        UserName = "Name: " + FirstName + " " + LastName;
                        Debug.Log(UserName); 
                    }
                }
            }
        }
    }

    void OnGUI()
    {
        Rect position = new Rect(60, 20, 400, 60);
        GUI.Label(position, UserName);
    }
}

I researched the same issue online, and many solutions said to install the NuGet package System.Data.SqlClient by Microsoft. I had already installed it in its most recent stable version (4.8.6), but the error does not disappear, it’s like if SqlConnection didn’t exist inside it.