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Articles by Jai Janardhan
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What is the use of MySQL IFNULL() control flow function?
MySQL IFNULL() control flow function will return the first argument if it is not NULL otherwise it returns the second argument.SyntaxIFNULL(expression1, expression2)Here if expression1 is not NULL then IFNULL() will return expression1 otherwise expression2. It will return NULL if both of the arguments are NULL. Following example will exhibit this −mysql> Select IFNULL(NULL, 'Ram'); +--------------------+ | IFNULL(NULL, 'Ram') | +--------------------+ | Ram | +--------------------+ 1 row in set (0.00 sec) mysql> Select IFNULL('Shyam', 'Ram'); +-----------------------+ | IFNULL('Shyam', 'Ram') | +-----------------------+ | Shyam ...
Read MoreHow MySQL FIELD() and ELT() functions are complements of each other?
On the basis of the working of both the functions, we can say that both are the complement of each other. Actually, as we know that FIELD() function, on providing a string as an argument, returns the index number of the string from string list and ELT() function, on providing index number as an argument, returns the string from string list. In the following example, we have applied both the functions on the same string, it would demonstrate the concept −Examplemysql> SELECT ELT(4, 'Ram', 'is', 'good', 'boy')As Result; +--------+ | Result | +--------+ | boy | +--------+ ...
Read MoreHow wildcard characters can be used with MySQL CONCAT() function?
As we know that wildcards are characters that help search data matching complex criteria. Wildcards are used in conjunction with LIKE comparison operator or NOT LIKE comparison operator. MySQL allows us to match the data, from the output of CONCAT() function, with the help of wildcard and comparison operators LIKE or NOT LIKE. An example from ‘Student’ table is given to make it clearer.Examplemysql> Select CONCAT(Name, ' ', Last_name) AS NAME from student Where CONCAT(Name, ' ', Last_Name) LIKE '%Kumar%'; +---------------+ | NAME | +---------------+ | Gaurav Kumar | | Harshit Kumar | +---------------+ ...
Read MoreHow can we update columns values on multiple rows with a single MySQL UPDATE statement?
Column values on multiple rows can be updated in a single UPDATE statement if the condition specified in WHERE clause matches multiple rows. In this case, the SET clause will be applied to all the matched rows.ExampleSuppose we have a table ‘tender’ as follows −mysql> Select * from tender; +-----------+---------+------+ | tender_id | company | rate | +-----------+---------+------+ | 200 | ABC | 1000 | | 300 | ABD | 5000 | | 301 | ABE | 6000 | | 302 ...
Read MoreHow can we apply a NOT NULL constraint to a column of an existing MySQL table?
We can apply the NOT NULL constraint to a column of an existing MySQL table with the help of ALTER TABLE statement. SyntaxALTER TABLE table_name MODIFY colum_name datatype NOT NULL; Examplemysql> Create table test123(ID INT, Date DATE); Query OK, 0 rows affected (0.19 sec) mysql> Describe test123; +-------+---------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+---------+------+-----+---------+-------+ | ID | int(11) | YES | | NULL | | | Date | date ...
Read MoreAdvantages and Disadvantages of the OSI Model
The advantages of the OSI model areIt is a generic model and acts as a guidance tool to develop any network model.It is a layered model. Changes are one layer do not affect other layers, provided that the interfaces between the layers do not change drastically.It distinctly separates services, interfaces, and protocols. Hence, it is flexible in nature. Protocols in each layer can be replaced very conveniently depending upon the nature of the network.It supports both connection-oriented services and connectionless services.The disadvantages of the OSI model areIt is purely a theoretical model that does not consider the availability of appropriate ...
Read MoreProtocol and Protocol Hierarchies
A protocol is a set of rules and conventions agreed upon and followed by the communicating entities for data communication. A protocol outlines the what, how and when of a communication.The three aspects of a protocol are −Syntax − It defines the format of data that is to be sent or received.Semantics − It defines the meaning of each section of bits that are transferred.Timings − It defines the time at which data is transferred as well as the speed at which it is transferred.Protocol HierarchiesMost networks are organized as a stack of layers, one on the top of another. ...
Read MoreConnection-Oriented Services
A connection-oriented service is one that establishes a dedicated connection between the communicating entities before data communication commences. It is modeled after the telephone system. To use a connection-oriented service, the user first establishes a connection, uses it and then releases it. In connection-oriented services, the data streams/packets are delivered to the receiver in the same order in which they have been sent by the sender.Connection-oriented services may be done in either of the following ways −Circuit-switched connection: In circuit switching, a dedicated physical path or a circuit is established between the communicating nodes and then data stream is transferred.Virtual circuit-switched ...
Read MoreComb Sort
The basic idea of comb sort and the bubble sort is same. In other words, comb sort is an improvement on the bubble sort. In the bubble sorting technique, the items are compared with the next item in each phase. But for the comb sort, the items are sorted in a specific gap. After completing each phase, the gap is decreased. The decreasing factor or the shrink factor for this sort is 1.3. It means that after completing each phase the gap is divided by 1.3.The complexity of Comb Sort TechniqueTime Complexity: O(n log n) for the best case. O(n^2/2^p) (p ...
Read MorePassing array to method in Java
Just as you can pass primitive type values to methods, you can also pass arrays to methods. For example, the following method displays the elements in an int array -Examplepublic static void printArray(int[] array) { for (int i = 0; i < array.length; i++) { System.out.print(array[i] + " "); } }You can invoke it by passing an array. For example, the following statement invokes the print Array method to display 3, 1, 2, 6, 4, and 2 -printArray(new int[]{3, 1, 2, 6, 4, 2});
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