Change a variable name in queried javascript object

I have this query in express js:

connection.connect();

var queryString = 'xxxxxxxxxxxxxxx';

connection.query(queryString, function(err, rows, fields) {
if (err) throw err;

for(var i in rows){
rows[i].bestPrice = rows[i].MIN(inventory.price);
delete rows[i].MIN(inventory.price);
}


res.writeHead(200, { 'Content-Type': 'application/json'});
res.end(JSON.stringify(rows););
});

connection.end();

It is querying some details about a laptop. The response JSON part looked like this before I added the for loop:

displayType: "LED"
vga: "Intel Graphics Media Accelerat"
partNumber: "A0100001"
MIN(inventory.price): "40000"

I want to change "MIN(inventory.price)" to "bestPrice", but it's not working. Any suggestion?