I'm trying to change visibility of all SIMPLE-only products via SQL.
Here is how I select all values of visibility attribute:
SELECT * FROM `catalog_product_entity_int` WHERE attribute_id = 102
SELECT * FROM `catalog_product_entity` WHERE `type_id`= 'simple'
as i got ur question, this simple code will be work for u.
i assume that relationship between these two tables are -entity_id
update catalog_product_entity_int set value =1 where attribute_id = 102 and entity_id= (select entity_id from `catalog_product_entity` where `type_id`= 'simple')