Select table name dynamically

Question

I want to create a cursor in which the select statement should be
dynamic:<o:p></o:p>
if @PhoneType = White<o:p></o:p>
Then the select statement should
be as<o:p></o:p>
select
distinct
MODEL_NUM from
Dbo.Apple<o:p></o:p>
if @PhoneType = Black<o:p></o:p>
select
distinct
MODEL_NUM from
Dbo.Samsung<o:p></o:p>
IF @MobileId
IS NOT NULL
         BEGIN
IF @PhoneType =
'white'
SET @SqlStmt
= 'select distinct MODEL_NUM from dbo.Apple'
IF @PhoneType =
'Black'
SET @SqlStmt
= 'select distinct MODEL_NUM from dbo.Samsung'
declare MOBILE
cursor for
select distinct
MODEL_NUM from Dbo.Apple

Answer 1

After a few decades with SQL, my rule of thumb is that you should write no more than five cursors in an entire career. Furthermore, dynamic SQL is how you tell the world you failed at your DDL and architecture, so you have to depend on future random users
to do your job. 
I also see you use if-then-else flow controls in SQL! This is a declarative language. We hate that kind of programming. 
Since you felt exempt from Netiquette and did post DDL, I will guess that the phones are set of entities which have a manufacturer. Putting them in separate tables is a design flaw called “attribute splitting” , much like having  “Male_Personnel” and “Female_Personnel”
instead of a Personnel table with a sex_code column. 
The skeleton for this kind of problem puts all the validation in a single table, thus: 
CREATE TABLE Phones 
 model_nbr VARCHAR (???) NOT NULL,
 manufacturer_name VARCHAR (???) NOT NULL,
 CONSTRAINT Valid_Model_nbr
  CHECK (CASE manufacturer_name 
         WHEN 'Apple' AND model_nbr LIKE '<reg exp>
         THEN 'T'
         WHEN 'Samsung' AND model_nbr LIKE '<reg exp>
         THEN 'T'
         ELSE 'F' END = 'T'),
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