When using the following mysql query:
select * from gc_product_attribute where (attribute_id = 30 AND text like '62') and (attribute_id = 35 AND text like '71')
The values exist in the table but nothing gets return
table below
attribute_id | text
30 | 62
35 | 71
You want to return the items that have (attribute_id = 30 AND text like '62') and the items that have (attribute_id = 35 AND text like '71').
This is different from retrieving the items that have (attribute_id = 30 AND text like '62') and have (attribute_id = 35 AND text like '71')
It can be expressed in two ways :
retrieve the items that satisfy X and also the items that satisfy Y : UNION
select * from gc_product_attribute where (attribute_id = 30 AND text like '62') UNION select * from gc_product_attribute where (attribute_id = 35 AND text like '71')
retrieve the items that satisfy either X or Y : OR
select * from gc_product_attribute where (attribute_id = 30 AND text like '62') OR (attribute_id = 35 AND text like '71')