text: -- e.g1
  SELECT DISTINCT
  Address AS 住所
  FROM
  Customers
  ;
  
  -- practice1
  SELECT DISTINCT
  HireFiscalYear
  FROM
  Employees
  ;
  
  
  -- practice2
  SELECT DISTINCT
  CustomerID,
  ProductID
  FROM
  Sales;
  
  -- practice3
  SELECT DISTINCT
  CustomerClassID,
  PrefecturalID
  FROM
  Customers;
  
  -- practice4
  SELECT DISTINCT
  CustomerID,
  ProductID,
  EmployeeID
  FROM
  Sales;
  
  -- practice5
  SELECT DISTINCT
  Price,
  CategoryID
  FROM
  Products;
  