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Articles on Trending Technologies
Technical articles with clear explanations and examples
Change the Auto Increment counter in MySQL?
In MySQL, auto increment counter starts from 0 by default, but if you want the auto increment to start from another number, use the below syntax.ALTER TABLE yourTable auto_increment=yourIntegerNumber;To understand the above syntax, let us first create a table. The query to create a table is as follows.mysql> create table startAutoIncrement -> ( -> Counter int auto_increment , -> primary key(Counter) -> ); Query OK, 0 rows affected (0.90 sec)Implement the above syntax to begin auto increment from 20. The query is as follows.mysql> alter table startAutoIncrement auto_increment=20; Query OK, 0 rows affected (0.30 sec) Records: 0 Duplicates: 0 Warnings: ...
Read MoreIs 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 MoreSelect values that meet different conditions on different rows in MySQL?
You can select values that meet different conditions on different rows using IN() and GROUP BY. The syntax is as follows −SELECT yourColumnName1 from yourTableName WHERE yourColumnName2 IN(value1, value2, .....N) GROUP BY yourColumnName1 HAVING COUNT(DISTINCT yourColumnName2)=conditionValue;To understand the above syntax, let us first create a table. The query to create a table is as follows −mysql> create table DifferentRows -> ( -> FirstRow int, -> SecondRow int -> ); Query OK, 0 rows affected (0.72 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into DifferentRows values(10, 10); Query OK, 1 row affected ...
Read MoreSELECT increment counter in MySQL?
To select increment counter in MySQL, first you need to declare and initialize a variable. The syntax is as follows −set @anyVariableName=0; select yourColumnName, @anyVariableName:=@anyVariableName+1 as anyVariableName from yourTableName;To understand the above syntax and set an increment counter, let us first create a table. The query to create a table is as follows.mysql> create table incrementCounterDemo -> ( -> Name varchar(100) -> ); Query OK, 0 rows affected (1.01 sec)Insert some records in the table using insert command. The query is as follows.mysql> insert into incrementCounterDemo values('John'); Query OK, 1 row affected (0.18 sec) mysql> insert into incrementCounterDemo values('Carol'); ...
Read MoreMySQL update with random number between 1 - 3
The syntax for updating a column with random number between 1-3 is is as follows −update yourTableName set yourColumnName=FLOOR(1+RAND()*3);To understand the above syntax, let us first create a table. The query to create a table is as follows −mysql> create table UpdateNumber1To3 -> ( -> MyNumber int -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into UpdateNumber1To3 values(100); Query OK, 1 row affected (0.16 sec) mysql> insert into UpdateNumber1To3 values(140); Query OK, 1 row affected (0.25 sec) mysql> insert into UpdateNumber1To3 values(130); ...
Read MoreHow to do a count on a MySQL union query?
To do a count on a union i.e. to get the count of the UNION result, use the below syntax −SELECT COUNT(*) FROM ( SELECT yourColumName1 from yourTableName1 UNION SELECT yourColumName1 from yourTableName2 ) anyVariableName;To understand the above syntax, let us create two tables with some records. The query to create a table is as follows −mysql> create table union_Table1 -> ( -> UserId int -> ); Query OK, 0 rows affected (0.47 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into union_Table1 values(1); Query OK, 1 row affected (0.18 sec) ...
Read MoreEuler's Totient function for all numbers smaller than or equal to n in java
Following is a program to get the result of Euler’s Totient function for all numbers smaller than or equal to n when n is given.Programimport java.util.Scanner; public class EulerTotient { public static int gcd(int a,int b){ int i, hcf = 0; for(i = 1; i
Read MoreEuler's criterion in java
According to Euler’s criterion a square root of n under modulo p exists if and only if a number num exists such that num%p is equal to n%p.Programimport java.util.Scanner; public class EulersCriterion { public static void main(String args[]) { Scanner sc = new Scanner(System.in); System.out.println("Enter n value :"); int n = sc.nextInt(); System.out.println("Enter p value :"); int p = sc.nextInt(); ...
Read MoreDivisors of factorials of a number in java
Following is a Java program to find the divisors of factorials of a number.Programimport java.util.Scanner; public class DivisorsOfFactorial { public static long fact(int i) { if(i
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 :"); ...
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