MongoDB Query Summary

1, including date query from the start time to the end time

Basicdbobject queryobj = new Basicdbobject ();

Queryobj.put ("Date", new Basicdbobject (). Append ("$gte", StartTime). Append ("$lt", Endtime));

2, DISTINCT query

Basicdbobject queryobj = new Basicdbobject ();

Coll.distinct ("Field_name", queryobj);//Field_name the field name that needs to be distinct in the database, queryobj as the query condition, after the query condition is executed in distinct ; Returns a list containing all the non-repeating field_name.

This approach still has a medium defect, if the data volume is too large list may exceed the capacity, bad control, you can use the group by method to replace

3, exists query

Basicdbobject basicobj = new Basicdbobject ();
Basicdbobject andsearch = new Basicdbobject ();

Andsearch.put ("$gte", Start.gettime ()), Andsearch.put ("$lt", End.gettime ()), Basicobj.put ("date", Andsearch);

Basicobj.put ("Field_name", New Basicdbobject ("$exists", true)); If the database field_name This field has a value (including null), then the condition is met, whereas this record does not have this field is not eligible

4.

MongoDB Query Summary