数据库查录问题

{
"list_cover": [
{
"type": {
"brand": "A",
"name": "A-01",
"memory": 16,
"cpu": 3.2
},
"category": "computer",
"quarter": "2020 Q2",
"price": 2500
},
{
"type": {
"brand": "X",
"name": "X-01",
"memory": 8,
"cpu": 4
},
"category": "computer",
"quarter": "2020 Q3",
"price": 6500
},
{
"type": {
"brand": "S",
"name": "S-01",
"author": "S-01-A"
},
"category": "book",
"quarter": "2020 Q3",
"price": 20
}
]
}
let res = await db.collection('record').where({
//'list_cover.quarter': dbCmd.eq('2020 Q2')
//'list_cover.quarter': '2020 Q2'
//'list_cover.quarter': new RegExp('^2020 Q2')

}).get()  
console.log('返回 : ', JSON.stringify(res.data));  

为什么用这三种方法返回都是全部返回
返回 : [{"_id":"60addbc29dad8500013591c5","list_cover":[{"type":{"brand":"A","name":"A-01","memory":16,"cpu":3.2},"category":"computer","quarter":"2020 Q2","price":2500},{"type":{"brand":"X","name":"X-01","memory":8,"cpu":4},"category":"computer","quarter":"2020 Q3","price":6500},{"type":{"brand":"S","name":"S-01","author":"S-01-A"},"category":"book","quarter":"2020 Q3","price":20}]}]