Difference between revisions of "Sort"
From NoSQLZoo
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Python does not store key order for dicts, so instead of the mongo shell <code>{<field1>:<value>,<field2>:<value>}</code> use <code>[(<field1>,<value>), (<field2>,<value>)]</code> | Python does not store key order for dicts, so instead of the mongo shell <code>{<field1>:<value>,<field2>:<value>}</code> use <code>[(<field1>,<value>), (<field2>,<value>)]</code> | ||
</div> | </div> | ||
| − | <div class="q nonum" data-lang=" | + | <div class="q nonum" data-lang="mongo">Sort all the documents in world by continent descending, then name ascending. Show only name and continent. |
<pre class=def> | <pre class=def> | ||
db.world.find({},{name:1,continent:1,_id:0}).sort([("continent",-1),("name",1)]) | db.world.find({},{name:1,continent:1,_id:0}).sort([("continent",-1),("name",1)]) | ||
Revision as of 15:22, 3 December 2015
sort() is a cursor method that orders the results of a query.
The aggregation framework provides the $sort operator, and map_reduce takes sort as a parameter that is applied to the input documents.
The syntax for sort() is sort(<field>:<value>) where 1 indicates ascending and -1 indicates descending.
The order in which fields are specified dictates which fields are sorted first.
Python does not store key order for dicts, so instead of the mongo shell {<field1>:<value>,<field2>:<value>} use [(<field1>,<value>), (<field2>,<value>)]
Sort all the documents in world by continent descending, then name ascending. Show only name and continent.
db.world.find({},{name:1,continent:1,_id:0}).sort([("continent",-1),("name",1)])