Question

I’m really struggling with a MySQL query that I’m really hoping someone can help me with. I have three tables in a MySQL database – Table A, B, and C. I would like to find all values from Table A, column 1 (a.1) that match a value in Table B column 2 (b.2). Then for each b.2 match, find all other b.2 values in Table B that are within a range of +/- 100 of the integer value found in b.3 within rows where a.1 matched b.2. Then finally I need to take these b.2 values and find matching b.2 values in Table C column 4.

Here is how I was trying to perform the query:

SELECT * 
FROM TableB AS b 
INNER JOIN TableA AS a ON b.2 = a.1 
AND b.3 >= (b.3 - 100) 
AND b.3 <= (b.3 + 100) 
INNER JOIN TableC as c 
ON b.2 = c.4;

I’ve tried to illustrate what I am trying to do with a picture, I hope this helps.

Answer 1

From your description I distilled this query:

SELECT a.one, b.three, c.four
FROM   a
JOIN   b AS b0 ON b0.two = a.one             -- intermediary step
JOIN   b ON b.three BETWEEN b0.three - 100 
                        AND b0.three + 100   -- real b values
JOIN   c ON c.four = b.two

Issues I see in your query:

• You have WHERE a.1 = b.2 where it should be ON a.1 = b.2
• In the final JOIN you have ON bb.3 = c.4, while according to your description it must be ON bb.2 = c.4.
• If your description is wrong and your demo is right, then we can simplify to:

SELECT a.one, b.three, c.four
FROM   a
JOIN   b ON b.two = a.one
JOIN   c ON c.four BETWEEN b.three - 100 AND b.three + 100