Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles on Trending Technologies
Technical articles with clear explanations and examples
Convert DATE timestamp to return the month number
To return only the month number, you can use DATE_FORMAT() -mysql> create table DemoTable1999 ( ArrivalDate timestamp ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1999 values('2019-01-01 12:34:00'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable1999 values('2019-12-31 10:04:00'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable1999 values('2018-10-11 04:04:30'); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select * from DemoTable1999;This will produce the following output −+---------------------+ | ArrivalDate ...
Read MoreMaximum average sum partition of an array in C++
Problem statementGiven an array, we partition a row of numbers A into at most K adjacent (non-empty) groups, then the score is the sum of the average of each group. What is the maximum score that can be scored?ExampleIf input array is {9, 2, 5, 3, 10} then we can partition array as follows −{9} {2, 5, 3} and {10} then average sum of this is −9 + (2 + 5 + 3)/ 3 + 10 = 22.33AlgorithmWe can use memorization technique to solve this problem −Let memo[i][k] be the best score portioning A[i to n-1] into at most K ...
Read MoreMaximum and Minimum in a square matrix in C++
Problem statementGiven a square matrix of order n*n, find the maximum and minimum from the matrixExampleIf given matrix is −{{15, 17, 19}, {5, 1, 7}, {14, 5, 16}} then Minimum number is 1 and maximum number is 19AlgorithmSelect two elements from the matrix one from the start of a row of the matrix another from the end of the same row of the matrixCompare them and next compare smaller of them to the minimum of the matrix and larger of them to the maximum of the matrix.We can see that for two elements we need 3 compare so for traversing ...
Read MoreSet multiple values for custom columns in MySQL?
For this, you can use UNION ALL. Let us first create a table −mysql> create table DemoTable1987 ( UserValue int ); Query OK, 0 rows affected (2.90 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1987 values(4); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable1987 values(5); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable1987 values(6); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable1987 values(7); Query OK, 1 row affected (0.09 sec)Display all records from the table using select statement −mysql> select * from DemoTable1987;This ...
Read MoreOnly display specified values inside the IN clause with MySQL?
For this, you can use IN() along with ORDER BY clause. Let us first create a table −mysql> create table DemoTable1986 ( Number int ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1986 values(50); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1986 values(60); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1986 values(100); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1986 values(200); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1986 values(350); Query OK, 1 row ...
Read MoreDate format to convert dates like Jan 2017, May 2018 to complete date in MySQL
For this, use STR_TO_DATE() along with DATE_FORMAT(). Let us first create a table −mysql> create table DemoTable1985 ( DueDate varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1985 values('Jan 2017'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1985 values('May 2018'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1985 values('Aug 2015'); Query OK, 1 row affected (0.00 sec)Display all records from the table using select statement −mysql> select * from DemoTable1985;This will produce the following output −+----------+ | DueDate | ...
Read MoreHow to insert a row with a timestamp "X days ago" in MySQL?
To insert a row like this use the following syntax, wherein we are using CURRENT_TIMESTAMP −insert into yourTableName values(CURRENT_TIMESTAMP - INTERVAL ABS(RAND() * 100) DAY);To understand the above syntax, let us create a table −mysql> create table DemoTable1983 ( DueDate timestamp ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1983 values(CURRENT_TIMESTAMP - INTERVAL ABS(RAND() * 100) DAY); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1983 values(CURRENT_TIMESTAMP - INTERVAL ABS(RAND() * 100) DAY); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1983 ...
Read MoreMySQL - changing table engine from innoDB to MyISAM?
Let us first create a table −mysql> create table DemoTable1982 ( StudentId int , StudentName varchar(20), StudentAge int ); Query OK, 0 rows affected (0.00 sec)Let us check the table engine type -mysql> show create table DemoTable1982;This will produce the following output −+---------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table ...
Read MoreMySQL query to calculate sum from 5 tables with a similar column named "UP"?
For this, use UNION ALL along with SUM(). Let us create 5 tables −mysql> create table DemoTable1977 ( UP int ); Query OK, 0 rows affected (0.00 sec) mysql> insert into DemoTable1977 values(10); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1977 values(20); Query OK, 1 row affected (0.00 sec) mysql> select * from DemoTable1977; +------+ | UP | +------+ | 10 | | 20 | +------+ 2 rows in set (0.00 sec) mysql> create table DemoTable1978 ( UP int ); Query OK, 0 rows affected (0.00 sec) mysql> ...
Read MoreUpdate a column A if null, else update column B, else if both columns are not null do nothing with MySQL
For this, use IF() with IS NULL property. Let us first create a table −mysql> create table DemoTable1976 ( FirstName varchar(20), LastName varchar(20) ); Query OK, 0 rows affected (0.00 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1976 values('John', 'Doe'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1976 values('John', NULL); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1976 values(NULL, 'Miller'); Query OK, 1 row affected (0.00 sec) mysql> insert into DemoTable1976 values('Chris', 'Brown'); Query OK, 1 row affected (0.00 sec)Display all records from the table ...
Read More