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You can delete a column in a table using the ALTER TABLE command.SyntaxALTER TABLE table_name DROP COLUMN column_name;Assume we have a table named Sales in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location as shown below:+----+-------------+--------------+--------------+--------------+-------+----------------+ | id | productname | CustomerName | DispatchDate | DeliveryTime | Price | Location | +----+-------------+--------------+--------------+--------------+-------+----------------+ | 1 | Key-Board | Raja | 2019-09-01 | 08:51:36 | 7000 | Hyderabad | | 2 | Earphones | Roja | 2019-05-01 ... Read More
To get all the MongoDB documents with some given criteria’s, following any of the below given casesCase 1 Following is the query to get all the documents without a single criterion using $ne operatordb.yourCollectionName.find({yourFieldName:{$ne:"yourValue"}}).pretty();Case 2 Following is the query to get all the documents without two given criterions using $nin operatordb.yourCollectionName.find({yourFieldName:{$nin:["yourValue1", "yourValue2"]}}).pretty();Let us first create a collection. Following is the query to create a collection with documents>db.findAllExceptFromOneOrtwoDemo.insertOne({"StudentName":"Larry", "StudentSubjectName":"Java"}); { "acknowledged" : true, "insertedId" : ObjectId("5c993d82330fd0aa0d2fe4d2") } >db.findAllExceptFromOneOrtwoDemo.insertOne({"StudentName":"Chris", "StudentSubjectName":"C++"}); { "acknowledged" : true, "insertedId" : ObjectId("5c993d8f330fd0aa0d2fe4d3") } >db.findAllExceptFromOneOrtwoDemo.insertOne({"StudentName":"Robert", "StudentSubjectName":"C"}); { "acknowledged" : true, "insertedId" : ObjectId("5c993d99330fd0aa0d2fe4d4") } ... Read More
To resize an image in iOS using swift we’ll make use of frame.Let’s see this with help of an example.Create an empty project and add an empty Image view.Create its outlet.Add an image to your project and assign the image to image view.Initially when we run the application, it looks something like this.Now, let’s add code to resize the image.override func viewWillLayoutSubviews() { let frame = CGRect(x: 10, y: 10, width: self.view.frame.width - 20, height: 300) self.imgView.frame = frame }We will run this code in our viewWillLayoutSubviews method. This is how it looks on the device when we ... Read More
Weakly or Strongly Connected for a given a directed graph can be find out using DFS. This is a C++ program of this problem.Functions usedBegin Function fillorder() = fill stack with all the vertices. a) Mark the current node as visited and print it b) Recur for all the vertices adjacent to this vertex c) All vertices reachable from v are processed by now, push v to Stack End Begin Function DFS() : a) Mark the current node as visited and print it b) Recur for all the vertices adjacent to this vertex ... Read More
To delete a MongoDB field and value, you can use $unset operator. Let us first create a collection with documents −> db.deleteFieldDemo.insertOne({"FirstName":"John", "LastName":"Smith"}); { "acknowledged" : true, "insertedId" : ObjectId("5cb9fb767219729fde21ddad") } > db.deleteFieldDemo.insertOne({"FirstName":"David", "LastName":"Miller"}); { "acknowledged" : true, "insertedId" : ObjectId("5cb9fb837219729fde21ddae") } > db.deleteFieldDemo.insertOne({"FirstName":"Carol", "LastName":"Taylor"}); { "acknowledged" : true, "insertedId" : ObjectId("5cb9fb8d7219729fde21ddaf") }Following is the query to display all documents from the collection with the help of find() method −> db.deleteFieldDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5cb9fb767219729fde21ddad"), "FirstName" : "John", "LastName" : "Smith" } { "_id" : ... Read More
You need to use DATE_FORMAT() for this. The syntax is as follows −SELECT DATE_FORMAT(yourColumnName, '%k:%i') as anyAliasName FROM yourTableName;You can use ‘%H:%i’ for the same result. To understand the above syntax, let us create a table.The query to create a table is as follows −mysql> create table TimeDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> LastLoginTime time -> ); Query OK, 0 rows affected (0.56 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into TimeDemo(LastLoginTime) values('09:30:35'); Query OK, 1 row affected ... Read More
The duration can be obtained in a one second format using the ofSeconds() method in the Duration class in Java. This method requires two parameters i.e. the number of seconds and the adjustment required in nanoseconds. Also, it returns the duration in a one second format. If the capacity of the duration is exceeded, then the ArithmeticException is thrown.A program that demonstrates this is given as follows −Example Live Demoimport java.time.Duration; public class Demo { public static void main(String[] args) { long seconds = 515793; long adjustment = 100; ... Read More
The iteration through Pair in JavaTuples is the same as you may have seen in Java Arrays collection.Let us first see what we need to work with JavaTuples. To work with Pair class in JavaTuples, you need to import the following package −import org.javatuples.Pair;Note − Steps to download and run JavaTuples program If you are using Eclipse IDE to run Pair Class in JavaTuples, then Right Click Project → Properties → Java Build Path → Add External Jars and upload the downloaded JavaTuples jar file.The following is an example −Exampleimport org.javatuples.Pair; public class Demo { public static void main(String[] ... Read More
To connect with a database, you need to follow the steps given below:Step1: Register the driver: To develop a basic JDBC application, first of all, you need to register the driver with the DriverManager.You can register a driver in two ways, one is using registerDriver() method of the DriverManager class and, using forName() method of the class named Class.The registerDriver() method accepts an object of the Driver class, it registers the specified Driver with the DriverManager.Driver myDriver = new com.mysql.jdbc.Driver(); DriverManager.registerDriver(myDriver);The forName() method loads the specified class into the memory and thus it automatically gets registered.Class.forName("com.mysql.jdbc.Driver");Step2: Get Connection: Get the ... Read More
JSP makes this job easy by providing you a mechanism where you can make a webpage in such a way that it would refresh automatically after a given interval.The simplest way of refreshing a Webpage is by using the setIntHeader() method of the response object. Following is the signature of this method −public void setIntHeader(String header, int headerValue)This method sends back the header "Refresh" to the browser along with an integer value which indicates time interval in seconds.Auto Page Refresh ExampleIn the following example, we will use the setIntHeader() method to set Refresh header. This will help simulate a digital ... Read More