MongoDB Common Chitian

2. Common commands

4. Show DBS Display Database list

   Use dbname into the dbname database, case sensitive, no this database does not matter

   Show Collections displays a collection in the database, equivalent to a table

6. Create & Add

   Db.users.save ({"Name": "LECAF"}) created a collection named users and added a new {"Name": "LECAF"} data

   Db.users.insert ({"Name": "Ghost", "Age": 10}) Inserts a new piece of data into the Users collection, and if there is no users this collection, MongoDB automatically creates

   There is a slight difference between save () and insert (): If the new data primary key already exists, insert () will not do the operation and prompt the error, while save () changes the original content to new content.

   Existing data: {_id:1, ' name ': ' N1 '}, _id is the primary key

   Insert ({_id:1, "name": "N2"}) will prompt for an error

   Save ({_id:1, "name": "N2"}) will change the N1 to N2, with the function of update.

8. Delete

   Db.users.remove () Delete all data under the Users collection

   Db.users.remove ({"Name": "LECAF"}) deletes data NAME=LECAF under the Users collection

   Db.users.drop () or Db.runcommand ({"Drop", "users"}) Delete collection users

   Db.runcommand ({"Dropdatabase": 1}) Delete the current database

10. Find

    Db.users.find () Find all data in the Users collection

    Db.users.findOne () to find the first data in the Users collection

12. Modify

    Db.users.update ({"Name": "LECAF"}, {"Age": 10}) modifies the NAME=LECAF data to age=10, the first parameter is the lookup condition, the second parameter is the modification, except the primary key, the other content is replaced by the contents of the second parameter , the primary key cannot be modified

13. Condition Lookup

    Db.collection.find ({"Key": value}) find data for Key=value

    Db.collection.find ({"key": {$gt: Value}}) key > value

    Db.collection.find ({"key": {$lt: Value}}) key < value

    Db.collection.find ({"key": {$gte: Value}}) key >= value

    Db.collection.find ({"key": {$lte: Value}}) key <= value

    Db.collection.find ({"key": {$gt: value1, $lt: value2}}) value1 < key <value2

    Db.collection.find ({"key": {$ne: Value}}) key <> value

    Db.collection.find ({"key": {$mod: [10, 1]}}) modulo operation, equal to key% 10 = = 1 i.e. key divided by 10 + 1

    Db.collection.find ({"key": {$nin: [1, 2, 3]}) does not belong, the condition equals the value of key does not belong to either [1, 2, 3]

    Db.collection.find ({"key": {$in: [1, 2, 3]}), the condition equals key equal to either [1, 2, 3]

    Db.collection.find ({"key": {$size: 1}}) $size number, size, condition equal to the number of values of key is 1 (key must be an array, a value can not be counted as an array of 1)

    Db.collection.find ({"key": {$exists: True|false}}) $exists field exists, true returns data with field key, FALSE returns data with no Word key

    Db.collection.find ({"Key":/^val.*val$/i}) regular, like; "I" Ignores case, "M" supports multiple lines

    Db.collection.find ({$or: [{a:1}, {b:2}]}) $or or (note: MongoDB 1.5.3 later versions are available), eligible a=1 or eligible b=2 data will be queried

    Db.collection.find ({"Key": Value, $or: [{a:1}, {b:2}]}) meets the criteria Key=value and matches any of the other two criteria

    Db.collection.find ({"Key.subkey": Value}) the values in the inline object match, note: "Key.subkey" must be quoted

    Db.collection.find ({"key": {$not:/^val.*val$/i}}) This is an operator that is used in combination with other query conditions and is not used alone. The result set obtained by the above query condition plus $not can get the opposite set.

15. Sort

    Db.collection.find (). Sort ({"Key1":-1, "Key2": 1}) Here the 1 stands for ascending,-1 for descending 8

17. Other

    Db.collection.find (). Limit (5) controls the number of returned results, and if the argument is 0, the limit () will not work if it is not constrained

    Db.collection.find (). Skip (5) controls how much the returned result skips, and if the argument is 0, then skip () will not work, or skip 0

    Db.collection.find (). Skip (5). Limit (5) can be used for paging, skipping 5 data and then fetching 5 data

    Db.collection.find (). Count (True) count () returns the number of result set bars

    Db.collection.find (). Skip (5). Limit (5). Count (True) to obtain the actual number of results returned when adding skip () and limit (), a parameter of true is required. Otherwise, the total number of results that match the query criteria is returned

MongoDB Common Chitian