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The deleteRow() method of the ResultSet interface deletes the current row from the current ResultSet object.//Deleting a column from the ResultSet object rs.deleteRow();Assume we have a table named Cricketers_Data with 6 records as shown below:+----+------------+------------+---------------+----------------+-------------+ | ID | First_Name | Last_Name | Year_Of_Birth | Place_Of_Birth | Country | +----+------------+------------+---------------+----------------+-------------+ | 1 | Shikhar | Dhawan | 1981-12-05 | Delhi | India | | 2 | Jonathan | Trott | 1981-04-22 | CapeTown | SouthAfrica | | 3 ... Read More
Python is a very versatile language as it provides huge set of libraries to work on different requirements. We all work on Portable Document Format (PDF) files. Python provides different ways to work with pdf files. In this we are going to use python library called PyPDF2 to work with pdf file.PyPDF2 is a pure-python PDF library capable of splitting, merging together, cropping, and transforming the pages of PDF files. It can also add custom data, viewing options, and passwords to PDF files. It can retrieve text and metadata from PDFs as well as merge entire files together.As we can ... Read More
In order to build multiple indexes at once, you need to use createIndexes() and pass multiple keys into an array. Following is the query for building multiple indexes at once.>db.multipleIndexesDemo.createIndexes([{"First":1}, {"Second":1}, {"Third":1}, {"Fourth":1}, {"Fifth":1}]);This will produce the following output{ "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 6, "ok" : 1 }Now get all the indexes> db.multipleIndexesDemo.getIndexes();This will produce the following output[ { "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_", ... Read More
Let us create a queue from LinkedList like this −Queuequeue = new LinkedList(); queue.add("P"); queue.add("Q"); queue.add("R"); queue.add("S"); queue.add("T"); queue.add("U"); queue.add("V");Now, use a List to display the elements of the queue −Listlist = new ArrayList(queue);Example Live Demoimport java.util.ArrayList; import java.util.LinkedList; import java.util.List; import java.util.Queue; public class Demo { public static void main(String[] args) { Queuequeue = new LinkedList(); queue.add("P"); queue.add("Q"); queue.add("R"); queue.add("S"); queue.add("T"); queue.add("U"); queue.add("V"); Listlist = new ArrayList(queue); for (Object ... Read More
To export specific column data in MySQL, use OUTFILE −select yourColumnName from yourTableName into outfile 'yourLocationOfFile’;Let us first create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentFirstName varchar(20), StudentLastName varchar(20) ); Query OK, 0 rows affected (0.54 sec)Insert records in the table using insert command −mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('John', 'Doe'); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('David', 'Miller'); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(StudentFirstName, StudentLastName) values('John', 'Smith'); Query OK, 1 row affected (0.15 sec) mysql> insert into ... Read More
A temporary file in the specified directory can be created using the method java.io.File.createTempFile(). This method requires three parameters i.e. the prefix to define the file name, the suffix to define the file extension and the directory in which the temporary file is to be created. It also returns the abstract path name for the temporary file created.A program that demonstrates this is given as follows −Exampleimport java.io.File; public class Demo { public static void main(String[] args) throws Exception { File directory = new File("C:/JavaProgram"); File file = File.createTempFile("temp", ".java", directory); ... Read More
The offset of the first element of the buffer inside the buffer array is obtained using the method arrayOffset() in the class java.nio.CharBuffer. If the buffer backed by the array is read-only, then the ReadOnlyBufferException is thrown.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 { CharBuffer buffer = CharBuffer.allocate(5); buffer.put('A'); buffer.put('P'); buffer.put('P'); ... Read More
The C++ function std::unordered_multimap::operator=() assigns new contents to the unordered_multimap by replacing old ones and modifies size if necessary.Following is the declaration for std::unordered_multimap::operator=() function form std::unordered_map() header.C++11 (Syntax)unordered_multimap& operator=(const unordered_multimap& umm);Parametersumm - Another unordered_multimap object of same type.Return ValueReturns this pointer.Example Code#include #include using namespace std; int main(void) { unordered_multimap umm1 = { {'a', 1}, {'b', 2}, {'c', 3}, {'d', 4}, {'e', 5}, }; unordered_multimap umm2; umm2 = umm1; cout
Let us convert string type to int for an example. Aggregation does not allow us to directly change the type of a field; therefore, you need to write a code to convert the type of a field.At first, create a collection with document. After that we will get the type of every field. The query to create a collection with document is as follows>db.changeDataType.insertOne({"StudentName":"Larry", "StudentAge":23, "StudentZipCode":" 10001", "isProgrammer":false}); { "acknowledged" : true, "insertedId" : ObjectId("5c6ed4976fd07954a4890694") }Display all documents from a collection with the help of find() method. The query is as follows:> db.changeDataType.find().pretty();The following is the output:{ ... Read More
When you are done with a user's session data, you have several options −Remove a particular attribute − You can call the public void removeAttribute(String name) method to delete the value associated with the particular key.Delete the whole session − You can call the public void invalidate() method to discard an entire session.Setting Session timeout − You can call the public void setMaxInactiveInterval(int interval) method to set the timeout for a session individually.Log the user out − The servers that support servlets 2.4, you can call logout to log the client out of the Web server and invalidate all sessions ... Read More