Need help with SQL subquery

Question

what i need is to be albe to select all the fields information from a table, where the name of the field from another table called "field_(and a number)"

i've tryed things like that but it didn't work...

SELECT  * 
FROM  `fieldList` 
WHERE ID =  "(SUBSTRING(SHOW FIELDS,5) FROM formList_5 LIKE  'field_%')"

and

SELECT  * 
FROM  `fieldList` 
WHERE ID =  "SUBSTRING((SHOW FIELDS FROM formList_5 LIKE  'field_%'),5)"

but it didn't work.

Answer 1

This is what you need:

SELECT *
FROM   `fieldlist`
WHERE  id IN (SELECT SUBSTRING(column_name, 5)
              FROM   information_schema.columns
              WHERE  table_name = 'formList_5'
              AND    column_name LIKE 'field_%')  

But, for sanity's sake, review your DB design if you can.