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MongoDB:查询和投影操作符

MongoDB查询和投影操作符。

官网:https://docs.mongodb.com/manual/reference/operator/query/。

这一章节都是很简单的英语,就做一个很简单的备注,如果连这个英语都看不懂,那就需要提高了,程序员看不懂基本的英语是很难提高的。
这一章节还需要完善一些样例,这个有待补充。

查询选择器

比较

名字 描述
$eq Matches values that are equal to a specified value.(判断相等)
$gt Matches values that are greater than a specified value.(判断大于)
$gte Matches values that are greater than or equal to a specified value.(判断大于等于)
$in Matches any of the values specified in an array.(判断在其中)
$lt Matches values that are less than a specified value.(判断小于)
$lte Matches values that are less than or equal to a specified value.(判断小于等于)
$ne Matches all values that are not equal to a specified value.(判断所有值都不等于指定值)
$nin Matches none of the values specified in an array.(判断不在其中)

逻辑

名字 描述
$and Joins query clauses with a logical AND returns all documents that match the conditions of both clauses.(与)
$not Inverts the effect of a query expression and returns documents that do not match the query expression.(非)
$nor Joins query clauses with a logical NOR returns all documents that fail to match both clauses.(异或)
$or Joins query clauses with a logical OR returns all documents that match the conditions of either clause.(或)

元素

名字 描述
$exists Matches documents that have the specified field.
$type Selects documents if a field is of the specified type.

评估

名字 描述
$expr Allows use of aggregation expressions within the query language.
$jsonSchema Validate documents against the given JSON Schema.
$mod Performs a modulo operation on the value of a field and selects documents with a specified result.
$regex Selects documents where values match a specified regular expression.
$text Performs text search.
$where Matches documents that satisfy a JavaScript expression.

地理空间

名字 描述
$geoIntersects Selects geometries that intersect with a GeoJSON geometry. The 2dsphere index supports $geoIntersects.
$geoWithin Selects geometries within a bounding GeoJSON geometry. The 2dsphere and 2d indexes support $geoWithin.
$near Returns geospatial objects in proximity to a point. Requires a geospatial index. The 2dsphere and 2d indexes support $near.
$nearSphere Returns geospatial objects in proximity to a point on a sphere. Requires a geospatial index. The 2dsphere and 2d indexes support $nearSphere.

数组

名字 描述
$all Matches arrays that contain all elements specified in the query.
$elemMatch Selects documents if element in the array field matches all the specified $elemMatch conditions.
$size Selects documents if the array field is a specified size.

位操作

名字 描述
$bitsAllClear Matches numeric or binary values in which a set of bit positions all have a value of 0.
$bitsAllSet Matches numeric or binary values in which a set of bit positions all have a value of 1.
$bitsAnyClear Matches numeric or binary values in which any bit from a set of bit positions has a value of 0.
$bitsAnySet Matches numeric or binary values in which any bit from a set of bit positions has a value of 1.

注释

名字 描述
$comment Adds a comment to a query predicate.

投影操作

名字 描述
$ Projects the first element in an array that matches the query condition.
$elemMatch Projects the first element in an array that matches the specified $elemMatch condition.
$meta Projects the document’s score assigned during $text operation.
$slice Limits the number of elements projected from an array. Supports skip and limit slices.