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Articles on Trending Technologies
Technical articles with clear explanations and examples
How can we know the repetition of a value in column with the help of group function COUNT(*) and GROUP BY clause?
We can use COUNT(*) and GROUP BY clause to find out the repetition of a value in the column. Following is the example, using COUNT(*) and GROUP BY clause on ‘Name’ column of table ‘Student’, to demonstrate it −mysql> select count(*), name from student group by name; +----------+---------+ | count(*) | name | +----------+---------+ | 1 | Aarav | | 2 | Gaurav | | 1 | Harshit | +----------+---------+ 3 ...
Read More0/1 Knapsack using Branch and Bound in C++
The idea is to implement the fact that the Greedy approach provides the best solution for Fractional Knapsack problem.To check whether a particular node can give us a better solution or not, we calculate the optimal solution (through the node) implementing Greedy approach. If the solution calculated by Greedy approach itself is more than the best so far, then we can’t obtain a better solution through the node.Complete Algorithm is given below −Sort all items according to decreasing order of ratio of value per unit weight so that an upper bound can becalculated implementing Greedy Approach.Initialize maximum profit, such as ...
Read MoreHow can I use 2-digit year value in MySQL DATEDIFF() function?
We can use 2-digit year value either in single date expression or in both date expressions used as argument/s in MySQL DATEDIFF() function.For example, the query below is using 2-digit year value in first date expression and other is having 4-digit year value.mysql> Select DATEDIFF('18-10-22', '2017-10-22'); +-----------------------------------+ | DATEDIFF('18-10-22', '2017-10-22') | +-----------------------------------+ | 365 | +-----------------------------------+ 1 row in set (0.00 sec)And the query below is using 2-digit year value in both date expressions.mysql> Select DATEDIFF('18-10-22', '17-10-22'); +---------------------------------+ | DATEDIFF('18-10-22', '17-10-22') | +---------------------------------+ | ...
Read MoreWhat is the range of date time value that we can pass as an argument to MySQL UNIX_TIMESTAMP function?
The range of date time value that we can pass as an argument to MySQL UNIX_TIMESTAMP function is the same as the range of TIMESTAMP data type i.e. between ‘1970-01-01 00:00:01’ to ‘2038-01-19 08:44:07’. If we give the date time values in UNIX_TIMESTAMP function beyond or below TIMESTAMP range, MySQL will return 0 as output. It can be understood with the help of the following example −mysql> select UNIX_TIMESTAMP('2038-01-19 08:44:07'); +---------------------------------------+ | UNIX_TIMESTAMP('2038-01-19 08:44:07') | +---------------------------------------+ | 2147483647 | +---------------------------------------+ 1 row in set (0.00 sec) ...
Read MoreWhat MySQL returns if I write only one value in the enclosed set of unit values for compound INTERVAL unit?
In this case, MySQL will take into consideration right most unit given in compound INTERVAL unit. It will return the output after calculating the interval on the basis of single value provided in the enclosed set of unit values. The following example will clarify it −mysql> Select TIMESTAMP('2017-10-22 04:05:36' + INTERVAL '2 ' year_month) AS 'Only Month Value Changed'; +--------------------------+ | Only Month Value Changed | +--------------------------+ | 2017-12-22 04:05:36 | +--------------------------+ 1 row in set (0.00 sec)The query above changes the month (right most in compound INTERVAL unit) from 10 to 12 based on the single value ...
Read MoreWhat MySQL returns if I use enclosed set of unit values with INTERVAL keyword?
In this case, MySQL will take into consideration the first value out of two provided in the enclosed set of unit values. It will return the output along with warning after calculating the interval, based on the considered value from an enclosed set, on the unit given in INTERVAL keyword. The following example will clarify it −mysql> Select TIMESTAMP('2017-10-22 04:05:36' + INTERVAL '4 2' Hour)AS 'HOUR VALUE INCREASED BY 4'; +---------------------------+ | HOUR VALUE INCREASED BY 4 | +---------------------------+ | 2017-10-22 08:05:36 | +---------------------------+ 1 row in set, 1 warning (0.00 sec) mysql> ...
Read MoreHow to sort MySQL output on the basis of the column which is not in the result set?
It is quite possible to get the sorted output on the basis of the column which is not even the part of that output or not in the result set. It can be done by selecting the required fields and writing the name of the fields on the basis of which sorting order is desired. Following is an example to demonstrate it, in which we sorted out the result set, having ‘Name’ and ‘Address’ fields, on the basis of column ‘id’.mysql> Select Name, Subject From Student ORDER BY Id; +---------+-----------+ | Name | Subject | +---------+-----------+ | Gaurav ...
Read MoreWhat MySQL returns if we include time components along with date component as an argument to DATEDIFF() function?
MySQL DATEDIFF() function also works with date and time values but it ignores the time value. Hence even if we include the time value in DATEDIFF() function MySQL will return the difference, in days, between dates by ignoring the time values.mysql> Select DATEDIFF('2018-10-22 04:05:36', '2017-10-22 03:05:45'); +-------------------------------------------------------+ | DATEDIFF('2018-10-22 04:05:36', '2017-10-22 03:05:45') | +-------------------------------------------------------+ | 365 | +-------------------------------------------------------+ 1 row in set (0.00 sec) mysql> Select DATEDIFF('2017-10-22 04:05:36', '2017-10-22 03:05:45'); +-------------------------------------------------------+ | DATEDIFF('2017-10-22 04:05:36', ...
Read MoreBinary Tree to Binary Search Tree Conversion using STL set C++?
In case of a given Binary Tree, convert it to a Binary Search Tree in such a way that keeps the original structure of Binary Tree intact.Sets of C++ STL will be used by this solution instead of array based solution.ExamplesExample 1Input 11 / \ 3 8 / \ 9 5Output 9 / \ 5 11 / \ 3 8Example 2Input 11 / \ 31 16 / \ 21 ...
Read MoreBinomial Heap in C++?
Binomial Heap is defined as an extension of Binary Heap that provides faster merge or union operation together with other operations provided by Binary Heap.A Binomial Heap is treated as a collection of Binomial Trees.What is a Binomial Tree?A Binomial Tree of order k can be built by taking two binomial trees of order k-1 and treating one as leftmost child or other.A Binomial Tree of order k has below properties.The number of nodes of Binomial Tree has exactly 2k.The depth of Binomial Tree is k.There are exactly kCi nodes at depth i where i = 0, 1, . . ...
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