If you run the Magento ecommerce shopping cart software and you want to find out how much your stock is worth, how many product lines you have stocked and how many individual items you have, you may find the following MySQL query handy.
I’m assuming that you’ve created an attribute with the attribute code “supplier_price” as a decimal, that you’ve kept this field up to date and your stock levels are accurate 
If it isn’t called “supplier_price” change the appropriate part in the query.
SELECT
COUNT(sku) AS 'products_stocked',
SUM(qty) AS 'items_in_stock',
SUM(stockvalue) AS 'stock_value'
FROM (
SELECT
catalog_product_entity.sku,
cataloginventory_stock_item.qty,
catalog_product_entity_decimal.value,
(cataloginventory_stock_item.qty * catalog_product_entity_decimal.value) AS stockvalue
FROM
cataloginventory_stock_item,
catalog_product_entity,
eav_attribute,
catalog_product_entity_decimal
WHERE
catalog_product_entity.type_id='simple' AND
cataloginventory_stock_item.product_id=catalog_product_entity.entity_id AND
catalog_product_entity_decimal.entity_id=catalog_product_entity.entity_id AND
eav_attribute.attribute_id=catalog_product_entity_decimal.attribute_id AND
eav_attribute.attribute_code='supplier_price' AND
cataloginventory_stock_item.qty > 0
ORDER BY sku ASC) AS b
I’ve decided to switch the back end of my side-line e-commerce 