这是一个创建于 1080 天前的主题，其中的信息可能已经有所发展或是发生改变。
[
{
"$group": {
"_id": "$username",
"total": {"$sum": 1}
}
}
]
想实现的是
select count(*) as total, * from table group by username
 |
1
namidairo 2021-12-10 08:59:04 +08:00
```
[ { $group: { _id: "$username", amount: {$sum: 1}, items: {$push: "$$ROOT"} } } ] ``` push: https://docs.mongodb.com/manual/reference/operator/aggregation/push/#mongodb-group-grp.-push $$ROOT: https://docs.mongodb.com/manual/reference/aggregation-variables/#mongodb-variable-variable.ROOT |
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