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Use $in operator to query an array of arrays in MongoDB. 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.arrayOfArraysDemo.insertOne({"EmployeeName":"Larry", "EmployeeSkills":[["Java", "MongoDB", "MySQL", "SQL Server"]]}); { "acknowledged" : true, "insertedId" : ObjectId("5c7f7a8d8d10a061296a3c5b") } > db.arrayOfArraysDemo.insertOne({"EmployeeName":"Mike", "EmployeeSkills":[["C", "C++"]]}); { "acknowledged" : true, "insertedId" : ObjectId("5c7f7aa68d10a061296a3c5c") }Display all documents from a collection with the help of find() method. The query is as follows −> db.arrayOfArraysDemo.find().pretty();The following is the output −{ "_id" : ObjectId("5c7f7a8d8d10a061296a3c5b"), "EmployeeName" : "Larry", "EmployeeSkills" : ... Read More
To insert a document with date in MongoDB, use Date(). Following is the syntax“yourFieldName”:new Date(yourDateValue);Let us create a collection with documents. Following is the query>db.insertDocumentWithDateDemo.insertOne({"UserName":"Larry", "UserMessage":"Hi", "UserMessagePostDate":new Date("2012-09-24")}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cca58a629b87623db1b16") } >db.insertDocumentWithDateDemo.insertOne({"UserName":"Chris", "UserMessage":"Hello", "UserMessagePostDate":new Date("2015-12-31")}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cca71a629b87623db1b17") } >db.insertDocumentWithDateDemo.insertOne({"UserName":"Robert", "UserMessage":"Bye", "UserMessagePostDate":new Date("2019-01-01")}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cca85a629b87623db1b18") }Following is the query to display all documents from a collection with the help of find() method> db.insertDocumentWithDateDemo.find().pretty();This will produce the following output{ "_id" : ObjectId("5c9cca58a629b87623db1b16"), "UserName" : "Larry", "UserMessage" : "Hi", ... Read More
Let us first create a List:List emp = Arrays.asList( new Employee("John", "Marketing", 5), new Employee("David", "Operations", 10));We have class Employee with name, department and rank of employees.Now, create summary for the rank like count, average, sum, etc:IntSummaryStatistics summary = emp .stream() .collect(Collectors.summarizingInt(p -> p.rank));The following is an example to create IntSummaryStatistics from Collectors in Java:Exampleimport java.util.Arrays; import java.util.IntSummaryStatistics; import java.util.List; import java.util.stream.Collectors; public class Demo { public static void main(String[] args) throws Exception { List emp = Arrays.asList(new Employee("John", "Marketing", 5), new Employee("David", "Operations", 10)); IntSummaryStatistics summary = emp .stream() .collect(Collectors.summarizingInt(p → ... Read More
The syntax to get names of all keys in the collection is as follows:var yourVariableName1=db.yourCollectionName.findOne(); for(var yourVariableName 2 in yourVariableName1) { print(yourVariableName); }To understand the above syntax, let us create a collection with documents. The collection name we are creating is “studentGetKeysDemo”.The following is the query to create documents:>db.studentGetKeysDemo.insert({"StudentId":1, "StudentName":"Larry", "StudentAge":23, "StudentAddress":"US", ... "StudentHobby":["Cricket", "Football", "ReadingNovel"], "StudentMathMarks":89, "StudentDOB":ISODate('1998-04-06')});The following is the output:WriteResult({ "nInserted" : 1 })Display all documents from a collection with the help of find() method. The query is as follows:> db.studentGetKeysDemo.find().pretty();The following is the output:{ "_id" : ObjectId("5c6c12dd68174aae23f5ef5f"), "StudentId" : 1, "StudentName" : ... Read More
The only safe way is to check for overflow before it occurs. There are some hacky ways of checking for integer overflow though. So if you're aiming for detecting overflow in unsigned int addition, you can check if the result is actually lesser than either values added. So for example, Example Codeunsigned int x, y; unsigned int value = x + y; bool overflow = value < x; // Alternatively "value < y" should also workThis is because if x and y are both unsigned ints, if added and they overflow, their values can't be greater than either of them ... Read More
To understand the concept, let us first create a table. The query to create a table is as followsmysql> create table ReorderSortDemo -> ( -> UserId int -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into ReorderSortDemo values(14); Query OK, 1 row affected (0.13 sec) mysql> insert into ReorderSortDemo values(4); Query OK, 1 row affected (0.10 sec) mysql> insert into ReorderSortDemo values(6); Query OK, 1 row affected (0.11 sec) mysql> insert into ReorderSortDemo values(3); Query ... Read More
You can insert null values into a table in SQL in two ways:Directly inserting the value NULL into the desired column as:Insert into SampleTable values (NULL);Using ‘ ’ as nullInsert into SampleTable values (NULL);While inserting data into a table using prepared statement object you can set null values to a column using the setNull() method of the PreparedStatement interface.pstmt.setNull(parameterIndex, sqlType);ExampleAssume we have a table named cricketers_data in the database with the following contents:+------------+------------+---------------+----------------+-------------+ | First_Name | Last_Name | Date_Of_Birth | Place_Of_Birth | Country | +------------+------------+---------------+----------------+-------------+ | Shikhar | Dhawan | 1981-12-05 | ... Read More
To delete multiple ids in MongoDB, you can use $in operator. Following is the syntaxdb.yourCollectionName.remove( { _id : { $in: [yourObjectId1, yourObjectId2, yourObjectId3)] } } );Let us create a collection with documents> db.deleteMultipleIdsDemo.insertOne({"ClientName":"Chris", "ClientAge":26}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cd7d6a629b87623db1b19") } > db.deleteMultipleIdsDemo.insertOne({"ClientName":"Robert", "ClientAge":28}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cd7dea629b87623db1b1a") } > db.deleteMultipleIdsDemo.insertOne({"ClientName":"Sam", "ClientAge":25}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cd7e9a629b87623db1b1b") } > db.deleteMultipleIdsDemo.insertOne({"ClientName":"John", "ClientAge":34}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cd7f7a629b87623db1b1c") } > db.deleteMultipleIdsDemo.insertOne({"ClientName":"Carol", "ClientAge":36}); { "acknowledged" : true, "insertedId" : ObjectId("5c9cd803a629b87623db1b1d") }Following is the query to ... Read More
You need to use SUBSTRING_INDEX() function from MySQL to extract part of a URL. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, URL text ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(URL) values('https:\www.example.com\homepage'); Query OK, 1 row affected (0.27 sec) mysql> insert into DemoTable(URL) values('https:\www.onlinetest.com\welcome\indexpage'); Query OK, 1 row affected (0.12 sec)Following is the query to display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output. Here, we can ... Read More
Use HTMLEditorKitt to change the font size with HTML. With that, use the JEditorPane setText() method to set HTML:HTMLEditorKit kit = new HTMLEditorKit(); editorPane.setEditorKit(kit); editorPane.setSize(size); editorPane.setOpaque(true); editorPane.setText(" This is a demo text with a different font!");The following is an example to change font size with HTML in Java Swing JEditorPane:Exampleimport java.awt.BorderLayout; import java.awt.Container; import java.awt.Dimension; import javax.swing.JEditorPane; import javax.swing.JFrame; import javax.swing.text.html.HTMLEditorKit; public class SwingDemo extends JFrame { public static void main(String[] args) { SwingDemo s = new SwingDemo(); s.setSize(600, 300); Container container = s.getContentPane(); s.demo(container, container.getSize()); ... Read More