confusing in mysql database tables

Question

i am bit confuse in to getting the result into the two tables, i know it is simple but not getting any clue.. here is my query the gives me the result, but when i am using the group by then it's just giving me the result of one line even the actual result in database is (300, 500) because i am fetching the result through the lead_id which is common in both tables..

SELECT inv.amount, crmd.computers, crmd.product_id, crmd.pc_opti
FROM invoice AS inv, lead_crm_data AS crmd
WHERE inv.lead_id = '310'
AND crmd.lead_id = '310'
GROUP BY inv.lead_id

here is the result of the given query..

amount  computers   product_id  pc_opti
300     2           7, 6            2
300     3           7, 6            3
540     2           7, 6            2
540     3           7, 6            3

result with GROUP BY

300     2           7, 6            2

Desired REsult

300     2           7, 6            2
540     3           7, 6            3

Answer 1

Try this:

SELECT inv.amount, crmd.computers, crmd.product_id, crmd.pc_opti
FROM invoice AS inv, lead_crm_data AS crmd
WHERE inv.lead_id = '310'
  AND crmd.lead_id = '310'
GROUP BY inv.amount

You could use a better (IMHO) syntax:

SELECT inv.amount, crmd.computers, crmd.product_id, crmd.pc_opti
FROM invoice AS inv INNER JOIN lead_crm_data AS crmd 
    ON inv.lead_id = crmd.lead_id 
   AND inv.lead_id = '310'
GROUP BY inv.amount