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To find items that do not have a certain field, use the $exists operator. The syntax is as follows −> db.yourCollectionName.find({"yourItemName":{$exists:false}}).pretty();To understand the syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.findDocumentDoNotHaveCertainFields.insertOne({"UserId":101, "UserName":"John", "UserAge":21}); { "acknowledged" : true, "insertedId" : ObjectId("5c8a95fb6cea1f28b7aa07fb") } > db.findDocumentDoNotHaveCertainFields.insertOne({"UserName":"David", "UserAge":22, "UserFavouriteSubject":["C", "Java"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c8a96116cea1f28b7aa07fc") } > db.findDocumentDoNotHaveCertainFields.insertOne({"UserName":"Bob", "UserAge":24, "UserFavouriteSubject":["MongoDB", "MySQL"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c8a96306cea1f28b7aa07fd") }Display all documents from a collection with the help of find() method. The ... Read More
In this we are going to use PyTorch to train a CNN to recognize handwritten digit classifier using the MNIST dataset.MNIST is a widely used dataset for hand-written classification task covering more than 70k labeled 28*28 pixel grayscale images of handwritten digits. The dataset contains almost 60k training images and 10k test images. Our job is to train a model using 60k training images and subsequently test its classification accuracy on 10k test images.InstallationFirst we need the MXNet latest version, for that just run the following on your terminal:$pip install mxnetAnd you will something like, Collecting mxnet Downloading https://files.pythonhosted.org/packages/60/6f/071f9ef51467f9f6cd35d1ad87156a29314033bbf78ad862a338b9eaf2e6/mxnet-1.2.0-py2.py3-none-win32.whl (12.8MB) ... Read More
A scope is a region of the program and broadly speaking there are three places, where variables can be declared −Inside a function or a block which is called local variables, In the definition of function parameters which is called formal parameters.Outside of all functions which is called global variables.We will learn what is a function and it's parameter in subsequent chapters. Here let us explain what are local and global variables.Local VariablesVariables that are declared inside a function or block are local variables. They can be used only by statements that are inside that function or block of code. ... Read More
To select min and max value from the part of a table in MySQL, use the following syntax −select min(yourColumnName) as yourAliasName1, max(yourColumnName) as yourAliasName2 from (select yourColumnName from yourTableName limit yourLimitValue) tbl1;Let us first create a table. Following is the query −mysql> create table MinAndMaxValueDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Value int -> ); Query OK, 0 rows affected (0.52 sec)Insert records in the table using insert command. Following is the query −mysql> insert into MinAndMaxValueDemo(Value) values(10); Query OK, 1 row affected (0.16 sec) mysql> insert into MinAndMaxValueDemo(Value) ... Read More
Bitcoins are created by Satoshi Nakamoto, in 2008 whose identity is still a mystery, whether it is one person or a group of persons. Satoshi Nakamoto proposed Bitcoin as a means of exchange, independent and secure and also a limited number.Now the question comes, Why limited supply?The most important feature of Bitcoin is that it is decentralized. No Central authority will keep a check on its demand or supply. Satoshi has created an open source code which is maintained by a group of volunteer programmers and runs as a distributed network with nodes spread across the world. We know that ... Read More
To convert date YYYYMMDD to YY-MM-DD in MySQL, use the below syntax −select date_format(str_to_date(yourColumnName, '%Y%m%d'), '%Y-%m-%d') from yourTableName;Let us first create a table −mysql> create table DemoTable ( ClientId int NOT NULL AUTO_INCREMENT PRIMARY KEY, ClientProjectDeadline varchar(200) ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command. We have inserted dates in the YYYYMMDD format −mysql> insert into DemoTable(ClientProjectDeadline) values('20121221'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(ClientProjectDeadline) values('20190416'); Query OK, 1 row affected (0.53 sec) mysql> insert into DemoTable(ClientProjectDeadline) values('20160624'); Query OK, 1 row affected (0.20 sec) mysql> ... Read More
Now you can command "Alexa, Create a new playlist " or "Alexa, add this to my playlist" and Alexa will obey your orders.Here is the know how ...You need Amazon music, as Alexa recognizes only Amazon music.Say "Alexa, create a new playlist" and Alexa will ask you to give the name of the playlist. Name the list. Now your playlist is created and ready.Now you have to add the required songs to the playlists with commands "Alexa, add this song to the playlist".You can even edit a playlist by taking the name of an already existing playlist.As of now deleting a ... Read More
The entries in the Provider have an unmodifiable set view that can be obtained using the method entrySet() in the class java.security.Provider. This method requires no parameters and it returns the unmodifiable set view for the entries in the Provider.A program that demonstrates this is given as follows −Example Live Demoimport java.security.*; import java.util.*; public class Demo { public static void main(String[] argv) { try { SecureRandom sRandom = SecureRandom.getInstance("SHA1PRNG"); Provider p = sRandom.getProvider(); Set set = p.entrySet(); Iterator i = ... Read More
The size of a struct type element taken by sizeof() is not always equal to the size of each individual member. Sometimes the compilers add some padding to avoid alignment issues. So the size may change. The padding is added when a structure member is followed by a member with a larger size or at the end of the structure. Different compiler has different types of alignment constraints. In C standard, the total alignment structure depends on the implementation.Case 1In this case the double z is 8-byte long, which is larger than x (4-byte). So another 4-byte padding is added. ... Read More
Before getting into example, we should know what sqlite data base in android is. SQLite is an open source SQL database that stores data to a text file on a device. Android comes in with built in SQLite database implementation. SQLite supports all the relational database features. In order to access this database, you don't need to establish any kind of connections for it like JDBC, ODBC etc.This example demonstrate about How to use unicode () in Android sqliteThis example demonstrate about How to use unicode () in Android sqliteStep 1 − Create a new project in Android Studio, go ... Read More