How to save and clean a specific database if there are 2 or more data?

Question

How to save and clean a specific database if there are 2 or more data models in one database file.

 

previously I have created a data model as below. I have successfully loaded the data into a listView for the public class student.

 

Then, how do you access data from a public class school that is only input once without using a listView and PrimaryKey?

using SQLite;
using System;
namespace SchoolData.Models {
  public class Student {
    [PrimaryKey, AutoIncrement] public int IdSis {
      get;
      set;
    }
    public DateTime Date {
      get;
      set;
    }
    public string PicStudent {
      get;
      set;
    }
  }
  public class School {
    public string SchoolName {
      get;
      set;
    }
    //without primary key or single entry
    public string Address {
      get;
      set;
    }
    public string Vision {
      get;
      set;
    }
  }
}

XamlPage code overview:

<StackLayout>
<Label Text="School Name:"/>
<Entry Text="{Binding SchoolName}"/>
<Label Text="Address:"/>
<Entry Text="{Binding Address}"/>
<Label Text="Vision:"/>
<Entry Text="{Binding Vision}"/>
<Button Text="Save" Clicked="SaveClick"/>
//save all entry
<Button Text="Clear" Clicked="ClearClick"/> //clear all entry
</StackLayout>

Thank's.