SQL - String Logic - sql

Question

I don't know if what I am wanting to achieve is possible so here is my conundrum.
Within a SQL table there are a number of fields that contain yes/no flags in a string so for example. On the field may be be called 'Stock' and within this one field there is a string of flags which e.g. 'YNYYY' lets say for example that the flags stand for.
Coke
Fanta
Pepsi
Lilt
Dr Pepper
in this instance I would want in my return of data to return Coke,Pepsi,Lilt,Dr Pepper ommiting the Fanta.
Now this would be possible using the CASE Statement and this may be the answer that I have to use, however ideally so I don't have to write hundreds of different variables anyone know of a way this could be achieved?
Your help as always appreciated, I've done the normal googling and maybe I simply don't know what to search for as its giving me blanks.
Please point me in the right direction.
Regards
R

Answer 1

Why dont you use SELECT with WHERE?
Something like this.
SELECT GROUP_CONCAT(`Stock`)
FROM table_name
WHERE `flag` = 'Y'
Hope this helps.

Answer 2

One way you can achieve your goal is by writing a table valued function that turns your Y/N string into a table of (Id INT, value BIT), you could then join to a look up table based on convention. Here's what something like this would look like:
CREATE FUNCTION udf_StringToBool(#intput varchar(100))
RETURNS #table TABLE (
Id INT IDENTITY(1,1),
Value BIT
)
AS
begin
declare #temp_input varchar(100) = #intput
while len(#temp_input) > 0
begin
insert into #table (value)
SELECT CASE LEFT(#temp_input, 1) WHEN 'Y' THEN 1 ELSE 0 END
set #temp_input = right(#temp_input, len(#temp_input)-1)
END
RETURN
end
You would then join your stock (and a lookup to product) table with this function, then remove any that are not in stock in the WHERE clause:
SELECT s.*, v.Value, pl.Name
FROM
stock s
cross apply
(
select b.* from udf_StringToBool(s.Flags) b
) v
join product_lookup pl on pl.Id = v.Id
WHERE v.Value = 1
Here's how you would define the lookup table:
create table product_lookup
(
Id INT IDENTITY(1,1),
Name Varchar(50)
)
insert into product_lookup (Name) values
('Coke'),
('Fanta'),
('Pepsi'),
('Lilt'),
('Dr Pepper')
Then you could use PIVOT to generate the columns with booleans.

Answer 3

In the end I chose to use 'substring' and the 'case' statement so that each item appeared in it's own field this way I mitigated the need to write every variable.
SELECT CASE WHEN SUBSTRING(STOCK,1,1) = 'y' THEN 'IN STOCK' ELSE 'OUTOFSTOCK' END AS COKE
I don't know why it didnt occur to me to begin with and without your prompting and guidance I would have probably done this the long way round as ever thanks to all!