How can I use FIND_IN_SET within a JOINED table?

Question

I have 2 tables:

• user: names of registered blood donors with their blood type.
• blood: contains blood types and blood com

Answer 1

You need to put the find_in_set() in the ON clause:

SELECT u.name AS name, b.name AS blood
FROM user u JOIN
     blood b
     ON FIND_IN_SET(u.id_blood, b.receive) > 0;

However, you should really have a separate table with one row per blood type and each type that can be received. This is called a junction table. Storing lists in comma-separated strings is not the SQL way of doing things: tables are.

EDIT:

Like this:

SELECT u.name AS name, b.name AS blood
FROM user u JOIN
     blood b
     ON FIND_IN_SET(u.id_blood, b.receive) > 0
WHERE u.id_blood = 5;