Row level security + Switch statement - sql

Question

I've a big table with lot of data who needs to have some RLS security.
The RLS is based on an other table (user logins with a profile number).
I've to make different logic of filtering depending on the profile number...
Let's say if the userProfile is 1 he can see all data.
If the user profile is 2 he can only see the data based on colA if he's 3 it's colB who have to be checked.
Example :
Profile | login Data | colA | colB
2 | toto data | toto | tutu
3 | tutu data | tata | tutu
I've tried to create a Switch statement based on profileType but it doesn't work. And i don't know if we can return a filtering in switch.
My try :
CREATE FUNCTION [dbo].[fn_rls_users](#username AS VARCHAR(50))
RETURNS TABLE
with schemabinding
AS
RETURN (
SELECT Department,ProfileType,
CASE
WHEN ProfileType = 1 THEN
RETURN (
SELECT 1 AS [fn_rls_users]
FROM BIG_TABLE
)
WHEN ProfileType = 2 THEN
RETURN (
SELECT 1 AS [fn_rls_users]
FROM BIG_TABLE
WHERE Department = Department
)
ELSE (
SELECT 0 AS [fn_rls_users]
FROM BIG_TABLE
)
END
FROM dbo.UserProfiles WHERE UserLogin = #username
)
GO
Any help appreciated

Answer 1

DECLARE #ProfileType date = (SELECT ProfileType FROM dbo.UserProfiles WHERE UserLogin = #username)
if #ProfileType = 1
select isnull(Data, 'NaN') from BIG_TABLE
else if #ProfileType = 2
select isnull(Data, 'NaN') from BIG_TABLE where colA = #username
else
select isnull(Data, 'NaN') from BIG_TABLE where colB = #username
End
Or, if you like using str exec
DECLARE #ProfileType date = (SELECT ProfileType FROM dbo.UserProfiles WHERE UserLogin = #username)
declare #str_sql varchar(1000)
set #str_sql = 'select isnull(Data, "NaN") from BIG_TABLE'
if #ProfileType = 2
set #str_sql += ' where colA = ' + #username
else if #ProfileType = 3
set #str_sql += ' where colB = ' + #username
exec(#str_sql)