search operation for CSV field sqlite

Question

I have a SQLite table named User . Each User has a primary UserID and multiple SecIDs (all integers). The SecIDs are stored in CSV format as a single field (type is String). For example, suppose User1 has SecIDs as 4,5,6,7 and User2 has SecIDs as 8,9,55,66.

So for User1 :-
UserID = 1
SecIDs = "4,5,6,7"
And for User2 :-
UserID = 2
SecIDs = "8,9,55,66" (And so on)

Now my question is- I have a particular SecID say 5. And I have to extract the UserID corresponding to that (which is 1). So what would be the Query for this operation?

PS- There could be hundreds of thousands of User Records in my SQLite table. So the search query should be an optimized for minimum time consumption.

Answer 1

That's simply not how you do SQL or relational databases, so SQLite doesn't have a specific SELECT syntax for that. You can of course search all the field by a String patter ~"12" , for example, but that is a terrible idea, because it matches 12 as much as 128 as much as 112.

What you should do is re-structure your database. Get a 1-to-n mapping table to map SecIDs to users; it's not hard at all, a lot faster, and but a two-column table:

+-----+----+
|SecID|User|
+-----+----+
|    4|   1|
|    5|   1|
|    6|   1|
|    7|   1|
|    8|   2|
|    9|   2|
|   55|   2|
|   66|   2|
+-----+----+

It will be much faster, less error-prone, and much more compact in both RAM and permanent storage.