MySQL LEFT JOIN problem.

[Scott Hamm]

SELECT
concat(associates.lastname,', ',associates.firstname) as Operator,
mrdaily.kronoshours as Hours,
mrdaily.pto as PTO,
mrcategories.category as Category,
mrentries.quantity as quantity,
mrentries.pages as pages,
mrentries.orders as orders,
mrentries.hours as hours,
round(mrentries.quantity/mrentries.hours,2) as 'Qty PPH',
round(mrentries.pages/mrentries.hours,2) as 'Pages PPH',
round(mrentries.orders/mrentries.hours,2) as 'Orders PPH'
FROM
mrentries,
associates,
mrdaily,
mrcategories
WHERE
mrentries.iddaily=mrdaily.id
AND
associates.id=mrdaily.idassociates
AND
entrydate='2004-08-03'
AND
mrcategories.id=mrentries.category;


+-----------------------------+-------+------+---------------------+----------+-------+--------+-------+---------+-----------+------------+
| Operator | Hours | PTO | Category | quantity | pages | orders | hours | Qty PPH | Pages PPH | Orders PPH |
+-----------------------------+-------+------+---------------------+----------+-------+--------+-------+---------+-----------+------------+
| Alexander, Lee | 8 | 0 | QA Taping PM | 2549 | 0 | 0 | 6.67 | 382.16 | 0.00 | 0.00 |
| Alexander, Lee | 8 | 0 | Admin | 0 | 0 | 0 | 0.58 | 0.00 | 0.00 | 0.00 |
| Anderson, Purlie | 6.33 | 0 | PM Orders | 90 | 0 | 0 | 2.17 | 41.47 | 0.00 | 0.00 |
| Anderson, Purlie | 6.33 | 0 | Survey | 73 | 0 | 0 | 1.42 | 51.41 | 0.00 | 0.00 |
| Anderson, Purlie | 6.33 | 0 | BlackLight | 55 | 0 | 0 | 1 | 55.00 | 0.00 | 0.00 |
| Anderson, Purlie | 6.33 | 0 | 10% Inspection | 17 | 0 | 0 | 1.33 | 12.78 | 0.00 | 0.00 |

How can I single out associates with each category on its own column using LEFT JOIN? I'm confused on how I should use LEFT JOIN, with mysql whining with errors.