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mongoDB如何query is Null

 
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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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