SQL meta key and meta value

i use SQL to get order with custom product. As i know meta value save in wp_woocommerce_order_itemmeta with serialized data.
So how to read that data in table resule of SQL.
I also see meta key of _wcpa in wp_postmeta . So which place should i get info of product that customer order in SQL query all orders?
Please give me an example of SQL query.