详解MongoDB的条件查询和排序

//  查找全部文档
db.collection.find({});
// 查找指定条件的文档
db.collection.find({key: value});
// 查找昵称为岛上码农的用户
db.users.find({nickname: '岛上码农'});

// AND 查询格式
db.collection.find({
  $and: [
    {key1: value1}, {key2: value2}
  ]
});

// OR 查询格式
db.collection.find({
  $or: [
    {key1: value1}, {key2: value2}
  ]
});

// NOT 查询格式
db.collection.find(
    {key: {$not: {条件表达式}}
);

[
  {nickname: '岛上码农', score: 90, gender: 'male'}, 
  {nickname: '玛丽', score: 98, gender: 'female'}, 
  {nickname: 'Tom', score: 76, gender: 'male'}
]

db.users.find({
  $or: [
    {score: 90}, {score: 76}
  ]
});

db.users.find({
  gender: {$not: {$eq: 'male'}}
});

db.users.find({
  score: {$not: {$lt: 80}}
});

// AND与OR 嵌套查询格式
db.collection.find({
  $and: [
    {$or: [{key1: value1}, {key2: value2}]},
    {$or: [{key3: value1}, {key4: value2}]},
  ]
});
//查找 nickename是岛上码农或玛丽,且分数是90或76的用户
db.users.find({
  $and: [
    {$or: [{nickname: '岛上码农'}, {nickname: '玛丽'}]},
    {$or: [{score: 90}, {score: 76}]}
  ]
});
//查找 nickname是岛上码农且分数是90，或nickname是玛丽且分数是76的用户
db.users.find({
  $or: [
    {$and: [{nickname: '岛上码农'}, {score: 90}]},
    {$and: [{nickname: '玛丽'}, {score: 76}]}
  ]
});
//查找nickname是岛上码农，且分数不低于80分的用户
db.users.find({
  $and: [
    {nickname: '岛上码农'},
    {score: {$not:{$lt: 80}}}
  ]
});

db.collection.find({key: {$in: [...]}});

db.users.find({score: {$in: [76, 90]}});

db.users.find({
 $and: [
   {score: {$in: [76, 90]}},
   {gender: 'male'}
   ]
});

// 查找指定条件的文档的 n 条数据
db.collection.find({key: value}).limit(n);
//示例：查询超过80分的3个用户
db.users.find({score: {$gt: 80}}).limit(3);
// 查找指定条件的文档的，跳过前 n 条数据
db.collection.find({key: value}).skip(n);
//示例： 查询超过80分的用户，跳过前3个
db.users.find({score: {$gt: 80}}).skip(3);

db.collection.find({条件}).sort({key: 1});

db.users.find().sort({score: -1});