weWe need to convert a dropdown attribute to multiselect
iI found a way here :
If attribute_code : age ,
entity_type_id = 10 ,
store_id = 1
If attribute_code : age , entity_type_id = 10 , store_id = 1
UPDATE eav_attribute SET
entity_type_id = '10',
attribute_model = NULL,
backend_model = 'eav/entity_attribute_backend_array',
backend_type = 'varchar',
backend_table = NULL,
frontend_model = NULL,
frontend_input = 'multiselect',
frontend_class = NULL
WHERE attribute_id = 'age';
Next, copy the attribute values from the old table to the new:
INSERT INTO catalog_product_entity_varchar ( 10, attribute_id, 1, entity_id, value)
SELECT entity_type_id, attribute_id, 1, entity_id, value
FROM catalog_product_entity_int
WHERE attribute_id = age;
Finally, remove the old values or they will conflict with the new setup (the old values will load, but Magento will save new values to the varchar table):
DELETE FROM catalog_product_entity_int
WHERE entity_type_id = 10 and attribute_id = age;
Credits :
http://swarminglabs.com/how-to-change-a-product-dropdown-attribute-to-a-multi-select/
but here i want to know how to find "attribute_id and entity_id" for an attribute. so i can replace those values in above queries