Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Cache is a type of memory that is used to increase the speed of data access. Normally, the data required for any process resides in the main memory. However, it is transferred to the cache memory temporarily if it is used frequently enough. The process of storing and accessing data from a cache is known as caching.Uncached System vs Cached SystemA figure to better understand the difference between cached and uncached system is as follows −Some important points to explain the above figureare −In an uncached system, there is no cache memory. So, all the data required by the processor ... Read More
It can be understood with the help of an example in which we would copy the values of a table into other table. We are using the data from table ‘cars’ and copy its data to table ‘copy_cars’ −mysql> CREATE TABLE copy_cars LIKE cars; Query OK, 0 rows affected (0.86 sec) mysql> SELECT * from copy_cars; Empty set (0.08 sec)The following query using the subquery will insert the values same as ‘cars’ to table ‘copy_cars’ −mysql> INSERT INTO Copy_cars Select * from Cars; Query OK, 8 rows affected (0.07 sec) mysql> SELECT * from copy_cars; +------+--------------+---------+ | ID ... Read More
The hot standby mode is a fail-safe in which a hot standby component is part of an active system. If any component of the system fails, the hot standby component takes its place. In general, a hot standby can refer to any device, system etc. that overtakes operation from a failed device and reduces the startup delay that would otherwise be huge.A figure to further explain the hot standby mode is as follows −In general, it is expected that a system will have some failures. So, a hot standby is necessary to combat these failures.At the extreme, a hot standby ... Read More
The fadeTo( ) method fades the opacity of all matched elements to a specified opacity and firing an optional callback after completion.Here is the description of all the parameters used by this method −speed - A string representing one of the three predefined speeds ("slow", "def", or "fast") or the number of milliseconds to run the animation (e.g. 1000).opacity − A number between 0 and 1 denoting the target opacity.callback − This is optional parameter representing a function to call once the animation is complete.You can try to run the following code to learn how to work with fadeTo() method ... Read More
It can be done by using UNIX_TIMESTAMP() function as follows −mysql> Select UNIX_TIMESTAMP(CONCAT(YEAR(CURDATE()),'-01-01')); +--------------------------------------------------+ | UNIX_TIMESTAMP(CONCAT(YEAR(CURDATE()),'-01-01')) | +--------------------------------------------------+ | 1483209000 | +--------------------------------------------------+ 1 row in set (0.03 sec)It can be verified by the following query −mysql> Select FROM_UNIXTIME(1483209000); +---------------------------+ | FROM_UNIXTIME(1483209000) | +---------------------------+ | 2017-01-01 00:00:00 | +---------------------------+ 1 row in set (0.02 sec)
To illustrate it we are using the following example of a table named ‘vistors’ which have the epoch as follows −mysql> Create table visitors(userid int not null, name varchar(20), epoch int NOT NULL); Query OK, 0 rows affected (0.42 sec) mysql> Insert into visitors Values(1, 'Gaurav', 1358658942); Query OK, 1 row affected (0.04 sec) mysql> Insert into visitors Values(2, 'Raman', 1358659585); Query OK, 1 row affected (0.04 sec) mysql> Select userid, name, FROM_UNIXTIME(epoch) from visitors; +--------+--------+----------------------+ | userid | name | FROM_UNIXTIME(epoch) | +--------+--------+----------------------+ | 1 | Gaurav | 2013-07-24 16:05:42 | | 2 | Raman | 2013-07-24 16:16:25 | +--------+--------+----------------------+ 2 rows in set (0.00 sec)
jQuery animate()The animate( ) method performs a custom animation of a set of CSS properties.Here is the description of all the parameters used by this method −params − A map of CSS properties that the animation will move toward.duration − This is optional parameter representing how long the animation will run.easing − This is optional parameter representing which easing function to use for the transition.callback − This is optional parameter representing a function to call once the animation is complete.You can try to run the following code to learn how to work with jQuery animate() method:Example Live Demo ... Read More
Group functions are the function which applied to a group of rows or in other words group functions operate on sets of values. The following table gives the Description of MySQL group functions −Sr.No.Name & Description1AVG()It returns the average value of the argument.2BIT_AND()It returns bitwise AND.3BIT_ORIt returns bitwise OR.4BIT_XOR()It returns bitwise XOR.5COUNT()It returns a count of the number of rows returned.6COUNT(DISTINCT)It returns the count of a number of different values.7GROUP_CONCAT()It returns a concatenated string.8MAX()It returns the maximum value.9MIN()It returns the minimum value.10ST()It returns the population standard deviation.11STDDEV()It returns the population standard deviation.12STDDEV_POP()It returns the population standard deviation.13STDDEV_SAMP()It returns the sample ... Read More
Following is the example of a stored function that can calculate the factorial of a given number −CREATE FUNCTION factorial (n DECIMAL(3,0)) RETURNS DECIMAL(20,0) DETERMINISTIC BEGIN DECLARE factorial DECIMAL(20,0) DEFAULT 1; DECLARE counter DECIMAL(3,0); SET counter = n; factorial_loop: REPEAT SET factorial = factorial * counter; SET counter = counter - 1; UNTIL counter = 1 END REPEAT; RETURN factorial; END // mysql> Select Factorial(5)// +--------------+ | Factorial(5) | +--------------+ | 120 | +--------------+ 1 row in set (0.27 sec) mysql> Select Factorial(6)// +--------------+ | Factorial(6) | +--------------+ | 720 | +--------------+ 1 row in set (0.00 sec)
If we have ALTER ROUTINE privileges then we can alter MySQL stored function with the help of ALTER FUNCTION query. Its syntax is as follows −SyntaxALTER FUNCTION function_name [characteristic ...] characteristic: { CONTAINS SQL | NO SQL | READS SQL DATA | MODIFIES SQL DATA } | SQL SECURITY { DEFINER | INVOKER } | COMMENT 'string'Here function_name is the name of the function which we want to alter.The ALTER FUNCTION statement can change the characteristics, defined above in the syntax, of a stored function. We can specify more than one change in an ALTER FUNCTION statement. But we ... Read More