mongodb.txt

*mongodb*
Insertions
    Inserting one new element
    *db.collection.insert_one(obj)
db.collection.insert_many(arr)*
    You can update all match entries with:
    *> db.collection.update({key : 'matchcriteria'}, {key : 'newvalue'})*

    You can delete a specific field with **$unset** you can add a new key with **$set**. You can add a new entry to an array with **$push** and **$pushall**:
    *> db.collection.update({}, { $unset : { key : 'alpha'}})*

    You can add multiple values to an array that matches:
    *> db.collection.update({}, { $push : { key : { $each : ['alpha', 'bravo']}}})*

    The function **$addtoset** has the same behaviour as **$push** but it only adds the element if it is not there

    The function **$pop** will remove a single element from an array. You can specify 1 to delete the last element or -1 to delete the first one.
    *> db.collection.update({{}, { $pop : {key : 1}}})*

    Delete all the elements that match:
    *> db.collection.update({{}, { $pull : {key : 'alpha'}})*

    drop a collection
    *> db.collection.drop()*

    Drop a database:
    *> db.dropDatabase()*

Search
    *show collections*

    *> db.collection.insert(document)*

    Find all elements in collection
    *> db.collection.find()*

    Find filtering elements:
    *> db.collection.find({key : 'value'})*

    Find skipping keys in the result:
    *> db.collection.find({}, {key : 0})*

    Find showing a single key in the result:
    *> db.collection.find({}, {key : 1})*

    Find filtering nested elements:
    *> db.collection.find({obj.key : 'value'})*

    Sort ascending by key:
    *> db.collection.find().sort(key: 1)*

    Sort descending by key:
    *> db.collection.find().sort(key: -1)*

    Limit the results to the first N:
    *> db.collection.find().limit(10)*

    Skip the first N results:
    *> db.collection.find().skip(10)*

    Return the number of elements that match:
    *> db.collection.count()*

    Return collection with key greater than:
    *> db.collection.find({key : { $gt : 10 }})*

    You can use the in operator to specify an array of possible values to match. Nin es the same but you specify the elements missing.
    *> db.collection.find({ key : { $in : [10, 15]}})*

    You can use the **$or** and **$and** operators:
    *> db.collection.find({$or : [ {key : 'alpha'}, {key : 'bravo'})*

    You can use the **$not** operator to negate a search.