To get a distinct aggregation of an array field across indexes, let us take an example and create a collection with some documents.Following is the query to create a collection with documents> db.distinctAggregation.insertOne({"UserName":"Larry", "UserPost":["Hi", "Hello"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c98aefb330fd0aa0d2fe4c6") } > db.distinctAggregation.insertOne({"UserName":"Chris", "UserPost":["Hi", "Good Morning"]}); ... Read More

For this, let us first create a new table in MySQLmysql> create table useProcedure - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > FirstName varchar(20), - > LastName varchar(20) - ... Read More

The count() method of the IntStream class in Java returns the count of elements in this streamThe syntax is as followslong count()First, create an IntStream and add some elementsIntStream intStream = IntStream.of(30, 13, 67, 56, 89, 99, 76, 56);Now, get the count of elements of the stream using the count() ... Read More

To specify exact order with where id IN, you need to use find_in_set() function.The syntax is as followsSELECT *FROM yourTableName WHERE yourColumnName IN (yourValue1, yourValue2, yourValue3, ....N) ORDER BY FIND_IN_SET(yourColumnName , ‘yourValue1, yourValue2, yourValue3, ....N’');Let us first create a tablemysql> create table FindInSetDemo    - > (    - > ... Read More

The max() method of the LongStream class in Java returns an OptionalLong describing the maximum element of this stream, or an empty optional if this stream is empty.The syntax is as followsOptionalLong max()Here, OptionalLong is a container object which may or may not contain a long value.To use the LongStream ... Read More

Let us first create a collection. Following is the query to create a collection with documents> db.documentExistsOrNotDemo.insertOne({"UserId":101, "UserName":"John"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9932bd330fd0aa0d2fe4cf") } > db.documentExistsOrNotDemo.insertOne({"UserId":102, "UserName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9932c6330fd0aa0d2fe4d0") } > db.documentExistsOrNotDemo.insertOne({"UserId":102, "UserName":"Robert"}); {    "acknowledged" : true,   ... Read More

ReferencesWhen a variable is declared as reference, it becomes an alternative name for an existing variable.SyntaxType &newname = existing name;InitializatioType &pointer; pointer = variable name;PointersPointers are used to store the address of variable.SyntaxType *pointer;InitializationType *pointer; pointer = variable name;The main differences between references and pointers are -References are used to ... Read More

Use aggregate() method to get all the non-distinct values of a field. Let us first create a collection with documents> db.findAllNonDistinctDemo.insertOne({"UserName":"John", "UserAge":28}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c995078863d6ffd454bb647") } > db.findAllNonDistinctDemo.insertOne({"UserName":"Larry", "UserAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c995081863d6ffd454bb648") } > db.findAllNonDistinctDemo.insertOne({"UserName":"Larry", "UserAge":23}); {   ... Read More

To get data from MySQL database, you need to use executeQuery() method from java. First create a table in the MySQL database. Here, we will create the following table in the ‘sample’ databasemysql> create table javaGetDataDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > ... Read More

The addIfAbsent() method appends the element if it is not in the list. If the element is already in the list, then FALSE is returned.The syntax is as follows.public boolean addIfAbsent(E ele)Here, ele is the element to be added to this list, if it is not already in the list.To ... Read More