[thelist] mySQL query

[Jay Blanchard]

[snip]
SELECT IT_D_id, IT_D_des, IT_D_wp, IT_D_wn, IT_D_s 
FROM `IT_D` id, `CAT` ca 
WHERE id.CA_id1 = ca.CA_id  
and ca.CAT_des='Chemical' 
order by IT_D_id desc limit 0,100

SELECT IT_D_id, IT_D_des, IT_D_wp, IT_D_wn, IT_D_s 
FROM `IT_D` id, `CAT` ca, `CAT` ca2 
WHERE id.CAT_id1 = ca.CAT_id 
and id.CAT_id2 = ca2.CAT_id 
and (ca.CAT_des='Chemical' or ca2.CAT_des='Chemical') 
order by IT_D_id desc limit 0,100
[/snip]

Try 

SELECT IT_D_id, IT_D_des, IT_D_wp, IT_D_wn, IT_D_s 
FROM `IT_D` id LEFT OUTER JOIN `CAT` ca
ON (id.CAT_id1 = ca.CAT_id)
LEFT OUTER JOIN `CAT` ca2 
ON (id.CAT_id2 = ca2.CAT_id)
WHERE ca.CAT_des='Chemical' 
order by IT_D_id desc limit 0,100

This is a little hard to accomplish via e-mail without table
descriptions and clearer column descriptors.