Right make SQL query's

Question

I try to make SQL queries but i can't do it right. I have one DB with 2 tables.The first table contains the ID and the words, and the second contains the ID and synonyms. I need to make three queries to the database to get the synonyms of one word entered, but the problem in the last query (as I consider). I even have instructions on how to create these questions correctly, but I'm stuck:

To start getting the words id query

SELECT id FROM words WHERE word = 'Profit'

. After that, we get a list of synonyms

SELECT w_id, s_id FROM synonyms  WHERE w_id = '1234 'or s_id = '1234'. 

Sort duplicate values ​​and pick synonyms

 SELECT word FROM words WHERE id IN (1,2,3,4,5 ...)

I think that instead of 1,2,3,4,5 must be previous query, but if I use it, the output is not given me anything or gives not what I need (ID instead of synonyms)

Data from table words: (1,'word1'),(2,'word2'),(3,'word3'),(4,'word4'),(5,'word5'),(6,'word6'),(7,'word7'),(8,'word8'), (9,'word9'),(10,'word10')

and from table synonyms: (1,2),(1,3),(1,4),(1,5),(1,6),(1,7),(1,8),(1,9),(1,10)

For example: If I write the word "word1"then the last query must find me all the synonyms related to it from the second table and display the result on the screen, but instead gives me the same word

Answer 1

Try this

SELECT sw.word 
FROM words w
INNER JOIN
    synonyms s ON
        s.w_id = w.id
INNER JOIN
    words sw ON
        sw.id = s.s_id
WHERE w.word = 'Profit'

You may also replace the 'Profit' by a variable and make this a function.

Answer 2

You must handle both directions; w_id → s_id, and s_id → w_id. There are several possible implementations; one is this:

SELECT word
FROM words
WHERE id IN (SELECT s_id
             FROM synonyms
             WHERE w_id = (SELECT id
                           FROM words
                           WHERE word = 'Profit'))
   OR id IN (SELECT w_id
             FROM synonyms
             WHERE s_id = (SELECT id
                           FROM words
                           WHERE word = 'Profit'))