user: Question: What's the total number of density for the place with a population over 393390?
Columns: ['English Name', 'Simplified', 'Traditional', 'Pinyin', 'Hakka', 'Area', 'Population', 'Density']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'real', 'real']
Sample row: ['Xinluo District', '新罗区', '新羅區', 'Xīnluó Qū', 'Sîn-lò-khî', 2685.0, 662429.0, 247.0]
SQL:

assistant: SELECT SUM("Density") FROM "Table" WHERE "Population" > 393390.0;