Accessing column value of table A using value from table B - mysql

Question

I've two tables say ABC and XYZ,
Table ABC:
B C ID ABC_ID
====================
50 30 10 2
60 31 11 3
Note: All the value fields are integers.
Table XYZ:
group condition value ID
================================
B = 50 10
C > 30 11
Note:
Column B and condition are varchar strings and value, ID columns are integers.
Using MySQL 5.5
I'm joining both the tables on the basis of column, ID.
There are many values for group in table XYZ and those values are columns in table ABC.
So, my questions are:
Once the ID matches, I will get the value of group as B in the above case from table XYZ. Then using the value, how should I get the value of B from table ABC?
I want to do something like :
select A.(X.group) from ABC A join XYZ X on A.ID = X.ID;
Once I'm able to get the value of column B using step 1 (as above), I need to form an expression like (group condition value) e.g. in able case B = 50 and replace the value of B from table ABC in the expression. The formed expression needs to be evaluated and if true, need to return the ABC_id from table ABC. How can I evaluate the expression?
I'm doing something like this:
select A.ABC_ID from XYZ X join ABC A on A.ID = X.ID where X.(A.group) A.condition A.value;
I've tried using PREPARE'ing and EXECUTE'ing but the join of ABC and XYZ would give multiple rows as a set. And it does not work.
SELECT X.group, X.condition, X.value
from XYZ X join ABC A
on X.ID = A.ID
into #colname, #condition, #value;
SET #qry = CONCAT('SELECT * from ABC WHERE ',#colname,#condition,#value);
PREPARE stmt FROM #qry;
EXECUTE stmt;
Thanks.

Answer 1

I created a sqlfiddle of this here: http://sqlfiddle.com/#!2/15e205/5
Note that I changed the names of group and condition because those are reserved words, and really aren't good choices for column names.
I'm using CONCAT() to build the query based on the values retrieved in XYZ.
SELECT grp, cndition, value
from XYZ
where id = 10
into #colname, #condition, #value;
SET #qry = CONCAT('SELECT * from abc WHERE ',#colname,#condition,#value);
PREPARE stmt FROM #qry;
EXECUTE stmt;