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The JavaServer Pages Standard Tag Library (JSTL) is a collection of useful JSP tags which encapsulates the core functionality common to many JSP applications.JSTL has support for common, structural tasks such as iteration and conditionals, tags for manipulating XML documents, internationalization tags, and SQL tags. It also provides a framework for integrating the existing custom tags with the JSTL tags.Install JSTL LibraryTo begin working with JSP pages you need to first install the JSTL library. If you are using the Apache Tomcat container, then follow these two steps −Step 1 − Download the binary distribution from Apache Standard Taglib and ... Read More
The time between two instant objects can be calculated using the until() method in the Instant class in Java. This method requires two parameters i.e. the end instant and the chronological unit to measure the time. It returns the time between two instant objects.A program that demonstrates this is given as follows −Example Live Demoimport java.time.*; import java.time.temporal.ChronoUnit; public class Demo { public static void main(String[] args) { Instant i1 = Instant.parse("2019-01-13T11:45:13.00Z"); Instant i2 = Instant.parse("2019-01-13T15:30:12.00Z"); long time = i1.until(i2, ... 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 work with CopyOnWriteArrayList class, you need to import the following package.import java.util.concurrent.CopyOnWriteArrayList;The following is an example to implement CopyOnWriteArrayList class addIfAbsent() method in Java.Example Live Demoimport java.util.concurrent.CopyOnWriteArrayList; public class Demo { public static void main(String[] args) { CopyOnWriteArrayList arrList = new CopyOnWriteArrayList(); arrList.add(30); arrList.add(40); ... Read More
To sort in ascending order, the syntax is as follows −db.yourCollectionName.find().sort({yourField:1});To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −> db.sortingDemo.insertOne({"Value":100}); { "acknowledged" : true, "insertedId" : ObjectId("5c8f8e2ed3c9d04998abf006") } > db.sortingDemo.insertOne({"Value":1}); { "acknowledged" : true, "insertedId" : ObjectId("5c8f8e31d3c9d04998abf007") } > db.sortingDemo.insertOne({"Value":150}); { "acknowledged" : true, "insertedId" : ObjectId("5c8f8e34d3c9d04998abf008") } > db.sortingDemo.insertOne({"Value":250}); { "acknowledged" : true, "insertedId" : ObjectId("5c8f8e37d3c9d04998abf009") } > db.sortingDemo.insertOne({"Value":5}); { "acknowledged" : true, "insertedId" : ObjectId("5c8f8e3bd3c9d04998abf00a") } > db.sortingDemo.insertOne({"Value":199}); { "acknowledged" : ... Read More
To select dates in 30-day range, you can use arithmetic operation - with interval.The syntax is as follows −select *from yourTableName where yourDateColumnName > NOW() - INTERVAL 30 DAY and yourDateColumnName < NOW() + INTERVAL 30 DAY;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table selectDatesDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ArrivalDate datetime -> ); Query OK, 0 rows affected (0.77 sec)Now you can insert some records in the table using insert command. The query is as ... Read More
You can add a unique constraint to a column using the ALTER TABLE commandSyntaxALTER TABLE table_name ADD CONSTRAINT MyUniqueConstraint UNIQUE(column1, column2...);Assume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:+--------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName | varchar(255) | YES | | NULL | | | CustomerName | varchar(255) | No | | NULL ... Read More
Access objects using dot notation. Let us first create a collection with documents> db.nestedObjectDemo.insertOne({"Student" : { "StudentDetails" : { "StudentPersonalDetails" : { "StudentName" : [ "John" ], ... "StudentCountryName" : [ "US" ], ... "StudentCoreSubject" : [ "C", "Java" ], ... "StudentProject" : [ "Online Book Store", "Pig Dice Game" ] } } } }); { "acknowledged" : true, "insertedId" : ObjectId("5c99dfc2863d6ffd454bb650") }Following is the query to display all documents from a collection with the help of find() method> db.nestedObjectDemo.find().pretty();This will produce the following output{ "_id" : ObjectId("5c99dfc2863d6ffd454bb650"), "Student" : { "StudentDetails" : ... Read More
This is C++ Program to Generate All Subsets of a Given Set in the Lexico Graphic Order. This algorithm prints all the possible combination of each length from the given set of array in increasing order. The time complexity of this algorithm is O(n*(2^n)).AlgorithmBegin For each length ‘i’ GenAllSubset() function is called: 1) In GenAllSubset(), if currLen is more than the reqLen then return. 2) Otherwise, if currLen is equal to reqLen then there will be a new sequence generated, print it. 3) If proceed with a start as ‘true’ and recursively call GenAllSubset() with incremented ... Read More
To query MongoDB using the $ne operator, following is the syntax −db.yourCollectionName.find({yourFieldName:{$ne:yourValue}}).pretty();Let us create a collection with documents −> db.notEqaulToDemo.insertOne({"StudentName":"Larry", "StudentMathMarks":68}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd3a6bde8cc557214c0ded") } > db.notEqaulToDemo.insertOne({"StudentName":"Chris", "StudentMathMarks":88}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd3a79de8cc557214c0dee") } > db.notEqaulToDemo.insertOne({"StudentName":"David", "StudentMathMarks":45}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd3a89de8cc557214c0def") } > db.notEqaulToDemo.insertOne({"StudentName":"Carol", "StudentMathMarks":69}); { "acknowledged" : true, "insertedId" : ObjectId("5cbd3a97de8cc557214c0df0") }Display all documents from a collection with the help of find() method −> db.notEqaulToDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cbd3a6bde8cc557214c0ded"), "StudentName" : "Larry", "StudentMathMarks" : ... Read More
You need to use MySQL event scheduler. It manages the execution of events as well as scheduling.First, you need to create a table. After that you can create a event that will schedule every single day.Let us create a table. The query to create a table is as follows −mysql> create table EventDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EventDateTime datetime -> ); Query OK, 0 rows affected (0.71 sec)Now you can insert some records in the table using insert command. The query ... Read More