1. shell
   1. db
   2. use database
   3. insert
   4. batchInsert
   5. update
   6. Upserts
      1. insert or update
   7. remove
   8. save
      1. if _id is exist it will update otherwise
   9. help
      1. db.help()
      2. db.mycoll.help()
      3. ...
   10. show
       1. show dbs
       2. show collections
       3. show users
       4. ...
   11. modifier
       1. $set
       2. $inc
          1. Incrementing
       3. decrementing
          1. Subtopic 1
   12. modifier array
       1. $push
       2. $addToSet
       3. $each
       4. $pop
       5. $pull
   13. db.getLastError()
   14. Query
       1. find
          1. example
             1. db.users.find({"username" : "joe", "age" : 27})
          2. Specifying Which Keys to Return
          3. Criteria
             1. $lt
             2. $lte
             3. $gt
             4. $gte
             5. $or
             6. db.raffle.find({"$or" : [{"ticket_no" : 725}, {"winner" : true}]})
             7. $in
             8. db.raffle.find({"ticket_no" : {"$in" : [725, 542, 390]}})
             9. $not
             10. db.users.find({"id_num" : {"$not" : {"$mod" : [5, 1]}}})
             11. $mod
             12. db.users.find({"id_num" : {"$mod" : [5, 1]}})
          4. Conditional Semantics
             1. db.users.find({"age" : {"$lt" : 30, "$gt" : 20}})
             2. db.users.find({"$and" : [{"x" : {"$lt" : 1}}, {"x" : 4}]})
          5. null
             1. list all
             2. db.c.find()
          6. array
             1. one of them
             2. $all
             3. match all
             4. $size
             5. $slice
          7. Embedded Documents
             1. Subtopic 1
          8. $where
       2. sort
       3. limit
       4. skip
       5. _addSpecial
          1. $maxscan
          2. $min
          3. $max
          4. $showDiskLoc
       6. explain
       7. hint
   15. Server-Side Scripting
       1. turn javascript off
          1. running mongod with the --noscripting option.
       2. use parameters like sql
   16. Cursors
       1. open
          1. var cursor = db.collection.find();
       2. cursor.hasNext()
       3. obj = cursor.next();
       4. forEach
   17. database command
       1. drop
       2. getLastError
       3. shutdown
2. data type
   1. null
   2. boolean
   3. number
   4. string
   5. date
   6. regular expression
   7. array
   8. embedded document
   9. object id
   10. binary data
   11. code
       1. JavaScript code:
3. Index
   1. ensureIndex
4. Aggregation
   1. aggregation framework lets you transform and combine documents in a collection
   2. pipeline
      1. filtering,
         1. projecting,
            1. grouping,
            2. sorting,
            3. limiting,
            4. skipping.
   3. example
   4. limited to 16 MB
   5. debug?
   6. function
      1. $match
      2. $project
         1. "$fieldname"
         2. Pipeline expressions
            1. Mathematical expressions.
            2. $add
            3. $subtract
            4. $multiply
            5. $divide
            6. $mod
            7. Date expressions.
            8. $year
            9. $month
            10. $week
            11. $dayOfMonth
            12. $dayOfWeek
            13. $dayOfYear
            14. $hour
            15. $minute
            16. $second
            17. String expressions.
            18. $substr
            19. $concat
            20. $toLower
            21. $toUpper
            22. Logical expressions.
            23. $cmp
            24. compare
            25. $strcasecmp
            26. "$eq"/"$ne"/"$gt"/"$gte"/"$lt"/"$lte"
            27. $and
            28. "$or"
            29. "$not"
            30. "$cond"
            31. "$ifNull"
      3. $group
         1. field name
            1. _id
            2. example
         2. operator
            1. $sum
            2. $average
            3. $avg
            4. $max
            5. $min
            6. $first
            7. $last
         3. Array operators.
            1. $addToSet
            2. $push
      4. $unwind
      5. $sort
      6. $limit
      7. $skip
5. MapReduce
   1. syntax
      1. db.[collection].mapReduce
         1. mapfunction
            1. this is the current document
            2. return
            3. emit(key, value);
         2. reduce function
            1. params
            2. key
            3. list of values above
            4. return newobject
         3. {}
            1. out
            2. outputs the results to a collection
            3. query
            4. finalize