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Articles by Chandu yadav
Page 53 of 81
How can I use MySQL OCTET_LENGTH() function to count the number of characters stored in a data column?
We need to pass the column name as the argument of OCTET_LENGTH() function to count the number of characters stored in a data column. It displays the number of characters when referenced in SELECT clause. It can also be used as comparison value to decide whether or not the row should returned by using it in WHERE clause. The contents of ‘Student’ table are used to demonstrate it −mysql> Select Name, OCTET_LENGTH(Name)As 'Str_Length' from Student; +---------+------------+ | Name | Str_Length | +---------+------------+ | Gaurav | 6 | | Aarav | 5 ...
Read MoreHow MySQL SUM() function evaluates if it got the column, having character data type, as its argument?
MySQL SUM() function will return 0, rather than NULL, along with a warning on getting the character type column as its argument. Following example using data from table named ‘Social’ will illustrate it −Examplemysql> Select * from Social; +------+-------+ | Id | Name | +------+-------+ | 100 | Rahul | +------+-------+ 1 row in set (0.00 sec) mysql> Select SUM(Name) From Social; +-----------+ | SUM(Name) | +-----------+ | 0 | +-----------+ 1 row in set, 1 warning (0.00 sec)
Read MoreWhat MySQL INSERT() function returns if the number of characters to be removed exceeds the number of characters available in original string?
In case if the number of characters to be removed exceeds the number of characters available in original string then MySQL INSERT() function will continue to remove the characters until the end of the original string.Examplemysql> Select INSERT('myteststring',3,15,'original'); +----------------------------------------+ | INSERT('myteststring',3,15,'original') | +----------------------------------------+ | myoriginal | +----------------------------------------+ 1 row in set (0.00 sec)
Read MoreWhat MySQL returns on running the INSERT INTO statement without giving the column name and values both?
When we run the INSERT INTO statement without giving the columns name/s and values both then MySQL will store NULL as the value of the column/s of table. Consider the example given below in which we have created a table ‘Student’ with the following query −mysql> Create table Student(RollNO INT, Name Varchar(20), Class Varchar(15)); Query OK, 0 rows affected (0.17 sec)Now, we can run INSERT INTO statement without giving the columns name/s and values both as follows −mysql> Insert into Student() Values(); Query OK, 1 row affected (0.02 sec)We can see from the query below MySQL stores NULL as the ...
Read MoreHow can we use MySQL INSTR() function with WHERE clause?
When we use INSTR() function with MySQL WHERE clause, we need to provide column name of the table as the first argument and the substring as second argument along with a comparison operator. Following is an example using ‘Student’ table to demonstrate it −ExampleSuppose we have the following values in ‘Student’ table −mysql> Select * from Student; +------+---------+---------+-----------+ | Id | Name | Address | Subject | +------+---------+---------+-----------+ | 1 | Gaurav | Delhi | Computers | | 2 | Aarav | Mumbai | History | | 15 | Harshit | ...
Read MoreHow can I manage the start position of searching in MySQL LOCATE() function?
As we know that by default searching in LOCATE() function starts from beginning. We can manage the start position by giving an argument to specify the position from which we want to start the search in string. Following example will demonstrate it −Examplemysql> Select LOCATE('good','Ram is a good boy. Is Ram a good boy?',11)As Result; +--------+ | Result | +--------+ | 29 | +--------+ 1 row in set (0.00 sec)In the above example, we have given the value 11 as the argument for position. It means that MySQL will start searching from 11th position.
Read MoreWhat is the way to get self-computed output from MySQL without a dummy table named dual?
In MySQL, we can simply specify the SELECT conditions all alone to get the self-computed output. Following example will demonstrate it −mysql> Select 1+1; +-----+ | 1+1 | +-----+ | 2 | +-----+ 1 row in set (0.02 sec) mysql> Select 1; +---+ | 1 | +---+ | 1 | +---+ 1 row in set (0.00 sec)
Read MoreHow can I change the value of an instance of a row in MySQL table?
UPDATE command along with WHERE clause can be used to change the value of an instance of a row. Basically, MySQL will change the value on the basis of the condition given in the query. Following example can demonstrate itSuppose we want to change the name from ‘Ram’ to ‘Mohit’ in the ‘testing’ table given below −mysql> Select * from testing; +----+---------+ | Id | Name | +----+---------+ | 1 | Harshit | | 2 | Lovkesh | | 3 | Ram | | 4 | Gaurav | +----+---------+ 4 rows in set (0.00 sec)Now ...
Read MoreLearn how to security patches or updates automatically on ubuntu
Are you using Ubuntu Server or Ubuntu system? then you should also be aware that, high profile banks are likely to be targeted by criminals looking for Server information/Files. Should you really worry?. maybe! This article provides you awareness on – Installing Security Patches for updating automatically on Ubuntu.Use the following command to install security patches automatically on Ubuntu$ sudo dpkg-reconfigure -plow unattended-upgradesWhile installing packages, it will ask permission from user as shown below –Now click on Ok by pressing enter key. Then, it will show the following screen as shown below-Now click on OK by pressing the enter key. The ...
Read MoreGreat tools to check linux disk partitions and usage in linux
Are you working as a system admin, then you should know these tools to manage disk space. This article explains about how to check Linux Disk Partitions and Usage in Linux.FdiskFdisk is a text based utility. By utilizing fdisk, you can create a brand new partition, delete the present partition, or exchange existing partition.To get the more information about fdisk, use the following command –$ fdiskThe sample out should be like this –Usage: fdisk [options] change partition table fdisk [options] -l [] list partition table(s) Display or manipulate a disk partition table. Options: -b, --sector-size ...
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