the update statement should look more like this:
UPDATE ps4_products
SET ps4_products.ProductPrice = _import_products.ProductPrice, ps4_products.ProductWeight = _import_products.ProductWeight, ps4_products.ProductWidth = _import_products.ProductWidth, ps4_products.ProductHeight = _import_products.ProductHeight, ps4_products.ProductLength = _import_products.ProductLength
FROM ps4_products, _import_products
WHERE _import_products.ProductSku = ps4_products.ProductSKU
see this page for an example:
update-data-in-one-table-with-data-from.html