user: Question: What is the density of 昌黎县?
Columns: ['Name', 'Hanzi', 'Hanyu Pinyin', 'Population (2004 est.)', 'Area (km²)', 'Density (/km²)']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['City proper', 'City proper', 'City proper', 'City proper', 'City proper', 'City proper']
SQL:

assistant: SELECT "Density (/km²)" FROM "Table" WHERE "Hanzi" = '昌黎县';