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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to detect if a MySQL database structure changed (not content)?
Let us first see an example and create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(40), StudentAge int, StudentMarks int ); Query OK, 0 rows affected (0.76 sec)Following is the query to know the database structure −mysql> show create table DemoTable;This will produce the following output −+---------------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table ...
Read MoreHow to deserialize a JSON array to list generic type in Java?
The Gson library provides a class called com.google.gson.reflect.TypeToken to store generic types by creating a Gson TypeToken class and pass the class type. Using this type, Gson can able to know the class passed in the generic class.Syntaxpublic class TypeToken extends ObjectWe can deserialize a JSON array to a generic type of list in the below exampleExampleimport java.lang.reflect.Type; import java.util.*; import com.google.gson.*; import com.google.gson.reflect.*; public class JSONArrayToListTest { public static void main(String args[]) throws Exception { String jsonStr = "[{"name":"Adithya", "course":"Java"}, " + "{"name":"Ravi", "course":"Python"}]"; ...
Read MoreWhat are different selenium versions?
Selenium 1 or known as RC (Remote Control) and Web Driver differ in many aspects but the key difference comes in the implementation layer or in simple words the architecture of both of them.As name suggest, RC is a Remote Control which works by taking the remote of the browser and then injects the automation code to be tested by injecting the custom scripts written.The Web Driver (known as Selenium 2) works on the browser directly and uses browsers in-built features to trigger the automation test written by tester. Web driver is the successor of Remote Control.The architecture of Selenium ...
Read MoreChange only dates, ignoring time records in MySQL
To change only dates, not time, use the MySQL INTERVAL and YEAR. Since, we will be updating the records, therefore, use UPDATE and set a new value with INTERVAL.Let us see an example and create a table −mysql> create table DemoTable ( DueDate datetime ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2017-08-12 10 :30 :45'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('2015-09-21 12 :00 :00'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('2018-12-31 11 :45 :56'); Query ...
Read MoreHow to count rows from two tables in a single MySQL query?
Let us first create a table −mysql> create table DemoTable1 ( Name varchar(40) ); Query OK, 0 rows affected (0.81 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values('Chris'); Query OK, 1 row affected (0.48 sec) mysql> insert into DemoTable1 values('Robert'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable1 values('Mike'); Query OK, 1 row affected (0.10 sec)Display all records from the table using select statement −mysql> select *from DemoTable1;This will produce the following output −+--------+ | Name | +--------+ | Chris | | Robert | | Mike | +--------+ ...
Read MoreMySQL query to generate row index (rank) in SELECT statement?
To generate a row index, use ROW_NUMBER(). Let us first create a table −mysql> create table DemoTable ( Name varchar(40) ); Query OK, 0 rows affected (0.49 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('Chris'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable values('Robert'); Query OK, 1 row affected (0.14 sec) mysql> insert into ...
Read MoreSearch text containing a new line in MySQL?
You can use REGEXP. Let us first create a table −mysql> create table DemoTable ( Name varchar(100) ); Query OK, 0 rows affected (1.61 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('JohnSmith'); Query OK, 1 row affected (0.73 sec) mysql> insert into DemoTable values('John Doe'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values('DavidMiller'); Query OK, 1 row affected (0.24 sec) mysql> insert into DemoTable values('Carol Taylor'); Query OK, 1 row affected (0.27 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following ...
Read MoreC++ Program to Compute the Area of a Triangle Using Determinants
In this section we will see how to find the area of a triangle in 2D coordinate space using matrix determinants. In this case we are considering the space is 2D. So we are putting each points in the matrix. Putting x values at the first column, y into the second and taking 1 as the third column. Then find the determinant of them. The area of the triangle will be half of the determinant value. If the determinant is negative, then simply take the absolute value of it.$$Area\:=\:absolute\:of\begin{pmatrix}\frac{1}{2} \begin{vmatrix} x_1\:\:y_1\:\:1 \ x_2\:\:y_2\:\:1 \ x_3\:\:y_3\:\:1 \end{vmatrix} \end{pmatrix}$$Here we are assuming ...
Read MoreRename multiple files using Java
Following is the code to rename multiple files using Java −Exampleimport java.io.File; import java.io.IOException; public class Demo{ public static void main(String[] argv) throws IOException{ String path_to_folder = "path\to\folder\where\multiple\files\are\present"; File my_folder = new File(path_to_folder); File[] array_file = my_folder.listFiles(); for (int i = 0; i < array_file.length; i++){ if (array_file[i].isFile()){ File my_file = new File(path_to_folder + "" + array_file[i].getName()); String long_file_name = array_file[i].getName(); String[] my_token = long_file_name.split("\s"); ...
Read MoreJar files in Java
JAR is a file format that helps in aggregating Java class file, along with its associated metadata and resources into a single file.Creation of a JAR file − The jar cf command can be used, where ‘cf’ means creating the file.jar cf jar_file_name files_to_compressOnce a jar file has been created, a default manifest file is also created. Only one manifest file is present in a specific archive, and it will have the extension ‘mf’ and will be in the pathname. Thismanifest file helps give information about the files that have been compressed/present in the package.Viewing a JAR file − The ...
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