MongoDB Query Document

When it comes to queries, we generally think of relational database queries, such as order by (sort), limit (paging), range query (greater than a value, less than a value), in queries, on queries, like queries waiting a lot, and MongoDB also supports these operations, Just different syntax, such as the sort: MongoDB inside using the Skip (field:1/-1) method, the following to introduce:

A. MongoDB Query document

1. Query the document find (): No condition is to query the collection of all the data

　　　　Syntax: Db.collectionName.find ({condition},{field:true/false})

1.1 Querying all data

　　　　　　

　　　　　　Displays the specified field (with contrast, find () the second parameter is the field of the specified query, the format [field name: True/false]true is displayed, False is not displayed):

　　　　　　

1.2 Query total data count ()

　　　　　　Syntax: Db.collectionName.find ({condition}). Count ()

　　　　　　

2. Querying a Document FindOne (): Default is the first document that the query meets the criteria

　　　　Syntax: Db.collectionName.findOne ({condition},{field:true/false})　　　　

　　　　

3.Pretty () method: Format The document that displays the query

　　　　

The conditional operators ("$and", "$nor", "$not", "$or", "$exists", "$mod", "$regex", "$where", "$slice ", "$elemMatch", "null query", "$all", "$size", "$in", "$nin")

1. The following is a list of conditional operators, meaning, syntax, and comparison with relational databases

Equals	{<key>:<value>}	db.col.find({"by":"zgw"})	where by = ‘zgw‘
Less than ($LT)	{<key>:{$lt:<value>}}	db.col.find({"likes":{$lt:50}})	where likes < 50
Less than or equal to ($lte)	{<key>:{$lte:<value>}}	db.col.find({"likes":{$lte:50}})	where likes <= 50
Greater than ($GT)	{<key>:{$gt:<value>}}	db.col.find({"likes":{$gt:50}})	where likes > 50
Greater than or equal to ($GTE)	{<key>:{$gte:<value>}}	db.col.find({"likes":{$gte:50}})	where likes >= 50
Not equal to ($ne)	{<key>:{$ne:<value>}}	db.col.find({"likes":{$ne:50}})	where likes != 50

　　

　　　　Syntax: Db.collectionName.find ({field:{operators1:value1,operators2:value2}})--[operators: These are the operators above ()]

PHP Format: Array (Field=>array (' $lte ' =>value)) or array (Field=>array (' $gte ' =>value1, ' $lte ' =>value2))

　　　　

The following is a query that is not equal to an operator:

　　　　

2. operators:"$and", "$nor", "$not", "$or", "$exists", "$mod", "$regex", "$where", "$slice", " $elemMatch "," null query "," $all "," $size "," $in "," $nin "

　　　　2.1 $and :

Continued: http://www.cnblogs.com/egger/p/3135847.html

Http://www.cnblogs.com/zhaoyang/archive/2012/01/10/2317664.html

　　

　　

MongoDB Query Document