试了半天,原来通过
db.taobaoItem.find({"coupon_price":{$ne:null}}
MongoDB Operators
Query Selectors
Comparison
Name
Description
$all |
Matches arrays that contain all elements specified in the query. |
$gt |
Matches values that are greater than the value specified in the query. |
$gte |
Matches values that are equal to or greater than the value specified in the query. |
$in |
Matches any of the values that exist in an array specified in the query. |
$lt |
Matches values that are less than the value specified in the query. |
$lte |
Matches values that are less than or equal to the value specified in the query. |
$ne |
Matches all values that are not equal to the value specified in the query. |
$nin |
Matches values that do not exist in an array specified to the query. |
Logical
Name
Description
$or |
Joins query clauses with a logical OR returns all documents that match the conditions of either clause. |
$and |
Joins query clauses with a logical AND returns all documents that match the conditions of both clauses. |
$not |
Inverts the effect of a query expression and returns documents that do not match the query expression. |
$nor |
Joins query clauses with a logical NOR returns all documents that fail to match both clauses. |
Element
Name
Description
$exists |
Matches documents that have the specified field. |
$mod |
Performs a modulo operation on the value of a field and selects documents with a specified result. |
$type |
Selects documents if a field is of the specified type. |
JavaScript
Name
Description
$where |
Matches documents that satisfy a JavaScript expression. |
$regex |
Selects documents where values match a specified regular expression. |
Geospatial
Name
Description
$geoWithin |
Selects geometries within a bounding GeoJSON geometry. |
$geoIntersects |
Selects geometries that intersect with a GeoJSON geometry. |
$near |
Returns geospatial objects in proximity to a point. |
$nearSphere |
Returns geospatial objects in proximity to a point on a sphere. |
Array
Name
Description
$elemMatch |
Selects documents if element in the array field matches all the specified $elemMatch condition. |
$size |
Selects documents if the array field is a specified size. |
Update Operators
Fields
Name
Description
$inc |
Increments the value of the field by the specified amount. |
$rename |
Renames a field. |
$setOnInsert |
Sets the value of a field upon documentation creation during an upsert. Has no effect on update operations that modify existing documents. |
$set |
Sets the value of a field in an existing document. |
$unset |
Removes the specified field from an existing document. |
Array
Operators
Name
Description
$ |
Acts as a placeholder to update the first element that matches the query condition in an update. |
$addToSet |
Adds elements to an existing array only if they do not already exist in the set. |
$pop |
Removes the first or last item of an array. |
$pullAll |
Removes multiple values from an array. |
$pull |
Removes items from an array that match a query statement. |
$pushAll |
Deprecated. Adds several items to an array. |
$push |
Adds an item to an array. |
Modifiers
Name
Description
$each |
Modifies the $push and $addToSet operators to append multiple items for array updates. |
$slice |
Modifies the $push operator to limit the size of updated arrays. |
$sort |
Modifies the $push operator to reorder documents stored in an array. |
Bitwise
Name
Description
$bit |
Performs bitwise AND and OR updates of integer values. |
Isolation
Name
Description
$isolated |
Modifies behavior of multi-updates to improve the isolation of the operation. |
Projection Operators
Name
Description
$ |
Projects the first element in an array that matches the query condition. |
$elemMatch |
Projects only the first element from an array that matches the specified $elemMatch condition. |
$slice |
Limits the number of elements projected from an array. Supports skip and limit slices. |
Meta-Query Operators
Query Modifiers
Name
Description
$comment |
Adds a comment to the query to identify queries in the database profiler output. |
$explain |
Forces MongoDB to report on query execution plans. See explain(). |
$hint |
Forces MongoDB to use a specific index. See hint()
|
$maxScan |
Limits the number of documents a cursor will return for a query. See limit(). |
$max |
Specifies a minimum exclusive upper limit for the index to use in a query. See max(). |
$min |
Specifies a minimum inclusive lower limit for the index to use in a query. See min(). |
$orderby |
Returns a cursor with documents sorted according to a sort specification. See sort(). |
$returnKey |
Forces the cursor to only return fields included in the index. |
$showDiskLoc |
Modifies the documents returned to include references to the on-disk location of each document. |
$snapshot |
Forces the query to use the index on the _id field. See snapshot(). |
Sort Order Specifier
Name
Description
$natural |
A special sort order that orders documents using the order of documents on disk. |
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