I just checked the product_options table schema and the it doesn't has the sku column. That's why you get the error. I think we should ask the AbanteCart developers add the sku in the next version.
SKU is not a part of the product_options table
SKU for option values stored in the ac_product_option_values and ac_order_options. The error usually appear if store was not upgraded correctly from older version to 1.2.12
Thanks for the information Basara.
Try to change COALESCE(po.sku,p.sku) to COALESCE(pov.sku,p.sku). Hope it works.