Help Needed in Relational logic

Question

Hi
Working in 2008 R2 version.
Below is the sample data to play with.
declare @users table (IDUser int primary key identity(100,1),name varchar(20),CompanyId int, ClientID int);
declare @Cards table (IdCard int primary key identity(1000,1),cardName varchar(50),cardURL varchar(50));
declare @usercards table (IdUserCard int primary key identity(1,1), IDUser int,IdCard int,userCardNumber bigint);
Declare @company table (CompanyID int primary key identity(1,1),name varchar(50),ClientID int);
Declare @client table (ClientID int primary key identity(1,1),name varchar(50));
Declare @company_cards table (IdcompanyCard int primary key identity(1,1),CompanyId int,IdCard int)
Declare @Client_cards table (IdclientCard int primary key identity(1,1),ClientID int,IdCard int)
insert into @users(name,CompanyId,ClientID)
select 'john',1,1 union all
select 'sam',1,1 union all
select 'peter',2,1 union all
select 'james',3,2
Insert into @usercards (IdUser,IdCard,userCardNumber)
select 100,1000,11234556 union all
select 100,1000,11234557 union all
select 100,1001,123222112 union all
select 200,1000,2222222 union all
select 200,1001,2222221 union all
select 200,1001,2222223 union all
select 200,1002,23454323 union all
select 300,1000,23454345 union all
select 300,1003,34543456;
insert into @Cards(cardName,cardURL)
select 'BOA','BOA.com' union all
select 'DCU','DCU.com' union all
select 'Citizen','Citizen.com' union all
select 'Citi','Citi.com' union all
select 'Americal Express','AME.com';
insert into @Client(name)
select 'AMC1' union all
select 'AMC2'
insert into @company(name,ClientId)
select 'Microsoft',1 union all
select 'Facebook',1 union all
select 'Google',2;
insert into @company_cards(CompanyId,IdCard)
select 1,1000 union all
select 1,1001 union all
select 1,1002 union all
select 1,1003 union all
select 2,1000 union all
select 2,1001 union all
select 2,1002;
Requirement : 
1. Get the distict Users card details. the reason for using distinct is, user can have same card multiple with different UserCardNumber.
Ex : user can have more than BOA card in the @usercards table with different UserCardNumber. But though he has two BOA card, my query should take one row.
2. After the 1st step, i need to check if any details on @company_cards based on Users companyId.If yes then selct the details from @company_cards. if not select it from @client_cards
In this case we need to make sure that we shouln't have repeated data on @FinalData table. 
My Logic:
Declare @FinalData table (IDCard int,CardName varchar(50),CardURL varchar(50))
declare @IdUser int = 100, @ClientID int,@companyID int;
select @ClientID = ClientID,@companyID = CompanyId from @users where IDUser = @IdUser;
insert into @FinalData (IDCard,CardName,CardURL)
Select distinct c.IdCard,c.cardName,c.cardURL from @usercards UC join @Cards C on(uc.IdCard = c.IdCard)
where IDUser=@IdUser;
if exists(select 1 from @company_cards where @companyID = @companyID)
BEGIN
insert into @FinalData(IDCard,CardName,CardURL)
select c.IdCard,c.cardName,c.cardURL from @company_cards cc join @Cards c on(cc.IdCard = c.IdCard) where CompanyId = @companyID
and cc.IdCard not in(select IDCard from @FinalData);
END
ELSE
BEGIN
insert into @FinalData(IDCard,CardName,CardURL)
select c.IdCard,c.cardName,c.cardURL from @client_cards cc join @Cards c on(cc.IdCard = c.IdCard) where ClientID = @ClientID
and cc.IdCard not in(select IDCard from @FinalData);
END
select * from @FinalData;
the logic produces the valid result. Is there any alternative way to achieve this logic. I feel there might be some proper way to query this kind of logic. any suggestion please.
[the sample schema and data i provided just to test. i didn't include the index and etc.]
loving dotnet

Answer 1

You can simply merge the statements like below
Declare @FinalData table (IDCard int,CardName varchar(50),CardURL varchar(50))
declare @IdUser int = 100
;With CTE
AS
Select IdCard, cardName, cardURL,
ROW_NUMBER() OVER (PARTITION BY IdCard ORDER BY Ord) AS Seq
FROM
Select c.IdCard,c.cardName,c.cardURL,1 AS Ord
from @usercards UC join @Cards C on(uc.IdCard = c.IdCard)
where IDUser=@IdUser
union all
select c.IdCard,c.cardName,c.cardURL,2
from @company_cards cc join @Cards c on(cc.IdCard = c.IdCard)
join @users u on u.CompanyId = cc.CompanyId
where u.IDUser = @IdUser
union all
select c.IdCard,c.cardName,c.cardURL,3
from @client_cards cc join @Cards c on(cc.IdCard = c.IdCard)
join @users u on u.ClientID= cc.ClientID
where u.IDUser = @IdUser
)t
insert into @FinalData (IDCard,CardName,CardURL)
SELECT IdCard, cardName, cardURL
FROM CTE
WHERE Seq = 1
select * from @FinalData;
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