Find primary key from one table in comma separated list

Question

I\'ve been given the task at work of creating a report based on a very poorly designed table structure.

Consider the following two tables. They contain techniques t

Answer 1

Using this function

Create FUNCTION F_SplitAsIntTable 
(
@txt varchar(max)
)
RETURNS 
@tab TABLE 
(
 ID int
)
AS
BEGIN
    declare @i int
    declare @s varchar(20)
    Set @i = CHARINDEX(',',@txt)
    While @i>1
        begin
          set @s = LEFT(@txt,@i-1)
          insert into @tab (id) values (@s)
          Set @txt=RIGHT(@txt,Len(@txt)-@i)
          Set @i = CHARINDEX(',',@txt)
        end
    insert into @tab (id) values (@txt) 
    RETURN 
END

You can query like this

declare  @a Table  (id int,Name varchar(10),Kind Varchar(100))
insert into @a values (1,'test','1,2,3,4'),(2,'test2','1,2,3,5'),(3,'test3','3,5')

Select a.ID,Name
from @a a
cross apply F_SplitAsIntTable(a.Kind) b 
where b.ID=2

Answer 2

I think this query looks cleaner:

SELECT p.*, 
t.Technique as ParsedTechnique
FROM Personnel p
JOIN Techniques t
ON CHARINDEX((','+CAST(t.id as varchar(10))+','), (','+p.technique+',')) > 0
WHERE t.id ='1';

You can just change the WHERE t.id = to whatever TechniqueId you need.

Fiddle Here

Answer 3

The first comment under the question provided the link to the answer. Here's what I ended up going with:

WHERE
   p.Technique LIKE '%,29,%' --middle
      OR
   p.Technique LIKE '29,%' --start
      OR
   p.Technique LIKE '%,29' --end
      OR 
   p.Technique =  '29' --single (good point by Cheran S in comment)

At initial glance I thought it wouldn't work, but clever use of % made it not match ids like 129, etc.

Answer 4

One of the problems you have to prevent is prevent "1" from matching "10" and "11". For this, you want to be sure that all values are delimited by the separator (in this case a comma).

Here is a method using like that should work effectively (although performance will not be so great):

SELECT p.*, t.Technique as ParsedTechnique
FROM Personnel p join
     Techniques t
     on ','+p.technique+',' like '%,'+cast(t.id as varchar(255))+',%'
WHERE t.id = 1;

If performance is an issue, then fix your data structure an include a PersonTechniques table so you can do a proper join.