问题
I run following query in mongo shell:
db.Profiles.find ( { $or: [ {\"name\": \"gary\"}, {\"name\": \"rob\"} ] } )
It just returns nothing as expected(JSON)?
回答1:
Use $in
For the query in the question, it's more appropriate to use $in
db.Profiles.find ( { "name" : { $in: ["gary", "rob"] } } );
Why doesn't it work
There's a missing quote - the cli is waiting for you to finish the second part of your or:
db.Profiles.find ( { $or : [ { "name" : "gary" }, {"name":"rob} ] } )
..............................................................^
You need to finish the query sufficiently for the cli to parse it for it to then say there's a syntax error.
Case insensitive matching
As indicated by a comment, if you want to search in a case insensitive manner, then you either use $or with a $regex:
db.Profiles.find ( { $or : [ { "name" : /^gary/i }, {"name": /^rob/i } ] } )
Or, you simply use one regex:
db.Profiles.find ( { "name" : /^(gary|rob)/i } )
However, a regex query that doesn't start with a fixed string cannot use an index (it cannot use an index and effectively do "start here until no match found then bail") and therefore is sub-optimal. If this is your requirement, it's a better idea to store a normalized name field (e.g. name_lc - lower case name) and query on that:
db.Profiles.find ( { "name_lc" : { $in: ["gary", "rob"] } } );
来源：https://stackoverflow.com/questions/14534984/mongodb-or-query