Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
A selector is an HTML tag at which a style will be applied. This could be any tag like or etc.With the type selector, set for HTML tags like h1, h2, h3, p, etc:h2 { color: #FFFF00; }Rather than selecting elements of a specific type, the universal selector simply matches the name of any element type:* { color: #FFFF00; }
Cascading Style Sheets, level 1 (CSS1) was came out of W3C as a recommendation in December 1996. This version describes the CSS language as well as a simple visual formatting model for all the HTML tags.CSS2 became a W3C recommendation in May 1998 and builds on CSS1. This version adds support for media-specific style sheets e.g. printers and aural devices, downloadable fonts, element positioning, and tables.CSS3 became a W3C recommendation in June 1999 and builds on older versions CSS. it has divided into documentation is called as Modules and here each module having new extension features defined in CSS2.CSS3 is ... Read More
Suppose you have created a Vector class to represent two-dimensional vectors, what happens when you use the plus operator to add them? Most likely Python will yell at you.You could, however, define the __add__ method in your class to perform vector addition and then the plus operator would behave as per expectation −Example Live Demo#!/usr/bin/python class Vector: def __init__(self, a, b): self.a = a self.b = b def __str__(self): return 'Vector (%d, %d)' % (self.a, self.b) def __add__(self, other): return Vector(self.a + other.a, self.b + other.b) v1 = ... Read More
We can use CONCAT() function to combine the values of two or more columns. In this case, the arguments of the CONCAT() functions would be the name of the columns. For example, suppose we have a table named ‘Student’ and we want the name and address of the student collectively in one column then the following query can be written −mysql> Select Id, Name, Address, CONCAT(ID, ', ', Name, ', ', Address)AS 'ID, Name, Address' from Student; +------+---------+---------+--------------------+ | Id | Name | Address | ID, Name, Address | +------+---------+---------+--------------------+ | 1 | Gaurav | Delhi ... Read More
Suppose from the table ‘Student’ we want to concatenate the values of columns, ‘Name’, ‘Address’ and ‘Columns’, based on the condition that is also a concatenation of values from columns, ’Name’, ‘Subject’, provided in WHERE clause with the help of CONCAT() function. We can use the following query to give the output −mysql> Select CONCAT(Name, ' ', 'Resident of', ' ', Address, ' ', 'is', ' ', 'Studying', ' ', Subject)AS 'Detail of Student' from Student WHERE CONCAT(Name, Subject) = "AaravHistory"; +----------------------------------------------+ | Detail of Student | ... Read More
Python deletes unneeded objects (built-in types or class instances) automatically to free the memory space. The process by which Python periodically reclaims blocks of memory that no longer are in use is termed Garbage Collection.Python's garbage collector runs during program execution and is triggered when an object's reference count reaches zero. An object's reference count changes as the number of aliases that point to it changes.An object's reference count increases when it is assigned a new name or placed in a container (list, tuple, or dictionary). The object's reference count decreases when it's deleted with del, its reference is reassigned, or ... Read More
MySQL CAST can handle overflow occurs during numerical expression assessment. Suppose if numeric expression evaluation produces overflow then MySQL reflects an error message. Now to handle this overflow we can change that numeric value to UNSIGNED with the help of CAST.For example on adding 1 to BIGINT maximum value, MySQL produce an error due to overflow as follows −mysql> Select 9223372036854775807 + 1; ERROR 1690 (22003): BIGINT value is out of range in '(9223372036854775807+1)'Now, with the help of CAST, MySQL handles this kind of overflow as follows:mysql> Select CAST(9223372036854775807 AS UNSIGNED) +1; +------------------------------------------+ | CAST(9223372036854775807 AS UNSIGNED) +1 | +------------------------------------------+ | 9223372036854775808 | +------------------------------------------+ 1 row in set (0.07 sec)
MySQL exact-value arithmetic can handle overflow occurs during numerical expression assessment because overflow occurs depends on the range of the operands. The values used in arithmetic expressions changed to other data type can put away the overflow.For example, after converting the BIGINT Maximum value to DECIMAL while adding 1 to it can handle the overflow as follows −mysql> Select 9223372036854775807.0 + 1; +---------------------------+ | 9223372036854775807.0 + 1 | +---------------------------+ | 9223372036854775808.0 | +---------------------------+ 1 row in set (0.01 sec)
In case of enabled SQL strict mode, subtraction between integers value in which one is of UNSIGNED type will produce an unsigned result by default. But MySQL produces an error if the result is a negative one. It can be observed with the following example −mysql> SET sql_mode = ''; Query OK, 0 rows affected (0.00 sec) mysql> Select CAST(0 AS UNSIGNED) -1; ERROR 1690 (22003): BIGINT UNSIGNED value is out of range in '(cast(0 as unsigned) - 1)'The error after the query above shows that it is an overflow after numeric arithmetic expression.Now, it can be handled with ... Read More
The class statement creates a new class definition. The name of the class immediately follows the keyword class followed by a colon as follows −class ClassName: 'Optional class documentation string' class_suiteThe class has a documentation string, which can be accessed via ClassName.__doc__.The class_suite consists of all the component statements defining class members, data attributes and functions.ExampleFollowing is the example of a simple Python class −class Employee: 'Common base class for all employees' empCount = 0 def __init__(self, name, salary): self.name = name self.salary = salary Employee.empCount += 1 def displayCount(self): ... Read More