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Articles by George John
Page 47 of 79
Is there any whoami function or command in MySQL like UNIX?
There is no whoami function in MySQL. The whoami can be used to know the current user in UNIX. Use user() or current_user() function from MySQL for the same purpose.The following is the output.+-----------+ | version() | +-----------+ | 8.0.12 | +-----------+ 1 row in set (0.00 sec)Case 1 −Using CURRENT_USER() function.The query to know the current user is as follows.mysql> select current_user();The following is the output.+----------------+ | current_user() | +----------------+ | root@% | +----------------+ 1 row in set (0.00 sec)Case 2 − Using USER() function.The query is as follows −mysql> select user();The following is ...
Read MoreLegendre's Formula in java
You can calculate the exponent of the largest power of a PrimeNumber that divides the factorial n! using Legendre's formula.Programimport java.util.Scanner; public class LegendresFormula { static int Largestpower(int n, int p) { int ans = 0; while (n > 0) { n /= p; ans += n; } return ans; } public static void main (String[] args) { Scanner sc = new Scanner(System.in); System.out.println("Enter the n value :"); ...
Read Morek-th prime factor of a given number in java
Following is the Java program which prints the kth prime factor of a number n, when k and n are given.Programimport java.util.Scanner; public class KthPrimeFactor { public static void main(String args[]) { int number, k, factor = 0; Scanner sc = new Scanner(System.in); System.out.println("Enter a number :"); number = sc.nextInt(); System.out.println("Enter the k value :"); k = sc.nextInt(); int temp = k-1; for(int i = 2; i< number; ...
Read MoreWhen running UPDATE ... datetime = NOW(); will all rows updated have the same date/ time in mysql?
The now() function returns the constant time that exhibits the time at which any statement began to execute. The sysdate() function returns the exact same datetime at which it executed the statement from MySQL 5.0.13.Suppose if you are updating datetime with now() in triggers or stored procedure, the now() method returns the time at which time the triggering and stored procedure begin to execute.Here is the demo of update with now(). Let us first create a table. The query to create a table is as follows −mysql> create table NowDemo -> ( -> DueDateTime datetime -> ); Query OK, 0 ...
Read MoreGet the index of last substring in a given string in MySQL?
To get the index of last substring in a given string, use the char_length() function. First, we need to calculate string length and subtract the last sub string length from the entire length. The difference in length is index of substring.SyntaxThe syntax is as follows −select CHAR_LENGTH(yourColumnName) - LOCATE('yourDelimiter ', REVERSE(yourColumnName))+1 as anyVariableName from yourTableName;To understand the above syntax, let us first create a table. The query to create a table is as follows −mysql> create table SubStringIndexDemo -> ( -> Words varchar(200) -> ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table ...
Read MoreCheck if table exist without using "select from" in MySQL?
We can achieve this with the help of SHOW command. Firstly, I will use my database with the help of USE command −mysql> USE business; Database changedWe are in the “business” database now. After that, we can check that how many tables are available for this database. The query is as follows −mysql> SHOW tables; The following is the output+------------------------+ | Tables_in_business | +------------------------+ | addcolumntable | | autoincrement | | autoincrementtable | | bookindexes | | chardemo ...
Read MoreHow to check if a column exist in a MySQL table?
To understand whether a column exist or not, we have the following approaches −With the help of DESC commandUsing SHOW commandFirstly, we will create a table with columns −mysql> CREATE table ColumnExistDemo -> ( -> UniqueId int, -> UniqueName varchar(200), -> UniqueAddress varchar(200) -> ); Query OK, 0 rows affected (0.57 sec)In the first approach, we will get the entire column name with meaningful information. The syntax is as follows −DESC yourTableName; Let us apply the above query to check whether the column name exists or not. However, this approach is not good since it display all the columns.mysql> DESC ...
Read MorePagination using MySQL LIMIT, OFFSET?
Firstly, we need to create a table with some records, then we will use pagination with the help of limit and offset.Creating a table with the help of CREATE command. The query is as follows −mysql> CREATE table limitoffsetDemo -> ( -> id int, -> FisrtName varchar(200) -> ); Query OK, 0 rows affected (0.45 sec)After creating a table, we will insert records with the help of INSERT command.Inserting recordsmysql> INSERT into limitoffsetDemo values(1, 'John'); Query OK, 1 row affected (0.11 sec) mysql> INSERT into limitoffsetDemo values(2, 'Bob'); Query OK, 1 row affected (0.16 sec) mysql> INSERT into ...
Read MoreWhat is unsigned in MySQL?
Unsigned allows us to enter positive value; you cannot give any negative number. Let us create a table to understand unsigned in MySQL. To create a table, we will use the CREATE command.Let us create a table −mysql> CREATE table UnsignedDemo -> ( -> id int unsigned -> ); Query OK, 0 rows affected (0.61 sec)After that I will insert only positive values. Let us insert some records −mysql> INSERT into UnsignedDemo values(124); Query OK, 1 row affected (0.09 sec) mysql> INSERT into UnsignedDemo values(78967); Query OK, 1 row affected (0.14 sec)I am displaying all the records with the ...
Read MoreWhat is the MySQL VARCHAR max size?
The MySQL version before 5.0.3 was capable of storing 255 characters but from the version 5.0.3 , it is capable of storing 65, 535 characters.MySQL official documentation states −The effective maximum length of a VARCHAR in MySQL 5.0.3 and later is subject to the maximum row size (65, 535 bytes, which is shared among all columns) and the character set used. For example, utf8 characters can require up to three bytes per character, so a VARCHAR column that uses the utf8 character set can be declared to be a maximum of 21, 844 characters. Keep in mind that the limitation of ...
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