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You can add a primary key constraint to a column of a table using the ALTER TABLE command.SyntaxALTER TABLE table_name ADD CONSTRAINT MyPrimaryKey PRIMARY KEY (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) | ... Read More
This is a C++ program to find SSSP (Single Source Shortest Path) in DAG (Directed Acyclic Graphs) using Dijkstra Algorithm to find out from the first node in graph to every other node with the shortest path length showed beside each pair of vertices.AlgorithmBegin Take the elements of the graph as input. function shortestpath(): Initialize the variables a[i] = 1 d[i] = 0 s[i].from = 0 Initialize a loop for i = 0 to 3 do if b[0][i] == 0 continue else ... Read More
A Hamiltonian cycle is a Hamiltonian Path such that there is an edge (in graph) from the last vertex to the first vertex of the Hamiltonian Path. It is in an undirected graph is a path that visits each vertex of the graph exactly once.Functions and purposesBegin 1. function isSafe() is used to check for whether it is adjacent to the previously added vertex and already not added. 2. function hamiltonianCycle() solves the hamiltonian problem. 3. function hamCycle() uses hamiltonianCycle() to solve the hamiltonian problem. It returns false if there is no Hamiltonian Cycle ... Read More
The syntax for multiple inserts for a single column in MySQL is as follows −INSERT INTO yourTableName(yourColumnName) values(‘yourValue1'), (‘yourValue2'), (‘yourValue3'), (‘yourValue4'), .........N;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table InsertMultipleDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserName varchar(10), -> UserRole varchar(20) -> , -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (3.14 sec)Now you can insert some records in the ... Read More
The equality of two buffers can be checked using the method equals() in the class java.nio.ByteBuffer. Two buffers are equal if they have the same type of elements, the same number of elements and the same sequence of elements. The method equals() returns true if the buffers are equal and false otherwise.A program that demonstrates this is given as follows −Example Live Demoimport java.nio.*; import java.util.*; public class Demo { public static void main(String[] args) { int n = 5; try { ... Read More
The duration can be obtained in a one nano second format using the ofNanos() method in the Duration class in Java. This method requires a single parameter i.e. the number of nano seconds and it returns the duration in a one nano 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 nanoseconds = 1000000000; Duration duration = ... Read More
The setAt2() method is used to set the Septet value in JavaTuples and a copy with a new value at the specified index i.e. index 2 here.Let us first see what we need to work with JavaTuples. To work with Septet class in JavaTuples, you need to import the following package −import org.javatuples.Septet;Note − Steps to download and run JavaTuples program If you are using Eclipse IDE to run Septet 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.Septet; ... 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, - > FirstName varchar(10), - > LastName varchar(10) - > ); Query OK, 0 rows affected (0.80 sec)Now you can insert some records in the table using insert command.The query is as followsmysql> insert into javaGetDataDemo(FirstName, LastName) values('John', 'Smith'); Query OK, 1 row affected (0.19 sec) mysql> insert into javaGetDataDemo(FirstName, LastName) values('Carol', ... Read More
Following is an example to send an email with attachment from your machine −Example Send Attachment Email using JSP Send Attachment Email using JSP Let us now run the above JSP to send a file as an attachment along with a message on a given email ID.User Authentication PartIf it is required to provide user ID and Password to the email server for authentication purpose, then you can set these properties as follows −Outputprops.setProperty("mail.user", "myuser"); props.setProperty("mail.password", "mypwd");
An immutable copy of a instant where some nanoseconds are subtracted from it can be obtained using the minusNanos() method in the Instant class in Java. This method requires a single parameter i.e. the number of nanoseconds to be subtracted and it returns the instant with the subtracted nanoseconds.A program that demonstrates this is given as follows −Example Live Demoimport java.time.*; public class Demo { public static void main(String[] args) { Instant i = Instant.now(); System.out.println("The current instant is: " + i); ... Read More