text: ---------------------------------------------------------------------
  -- LAB 08
  --
  -- Exercise 3
  ---------------------------------------------------------------------
  
  USE TSQL;
  GO
  
  ---------------------------------------------------------------------
  -- Task 1
  ---------------------------------------------------------------------
  
  SELECT contactname, COALESCE(fax, N'No information') AS faxinformation
  FROM Sales.Customers;
  
  SELECT contactname, ISNULL(fax, N'No information') AS faxinformation
  FROM Sales.Customers;
  
  ---------------------------------------------------------------------
  -- Task 2
  ---------------------------------------------------------------------
  
  DECLARE @region AS NVARCHAR(30) = NULL; 
  
  SELECT 
  	custid, region
  FROM Sales.Customers
  WHERE region = @region OR (region IS NULL AND @region IS NULL);
  
  GO
  
  DECLARE @region AS NVARCHAR(30) = N'WA'; 
  
  SELECT 
  	custid, region
  FROM Sales.Customers
  WHERE region = @region OR (region IS NULL AND @region IS NULL);
  
  ---------------------------------------------------------------------
  -- Task 3
  ---------------------------------------------------------------------
  
  SELECT custid, contactname, city, region
  FROM Sales.Customers 
  WHERE 
  	region IS NULL 
  	OR LEN(region) <> 2;
  