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Articles on Trending Technologies
Technical articles with clear explanations and examples
Filter in Python
We sometimes arrive at a situation where we have two lists and we want to check whether each item from the smaller list is present in the bigger list or not. In such case we use the filter() function as discussed below.SyntaxFilter(function_name, sequence name)Here Function_name is the name of the function which has the filter criteria. Sequence name is the sequence which has elements that needs to be filtered. It can be sets, lists, tuples, or other iterators.ExampleIn the below example we take a bigger list of some month names and then filter out those months which does not have ...
Read MoreIs there a way to subtract number of days from a date in MySQL?
Yes, you can use date_sub() to subtract number of days from a date. Following is the syntax −select date_sub(yourColumnName, Interval yourAmountOfDays day) from yourTableName;Let us first create a table −mysql> create table DemoTable660(AdmissionDate datetime); Query OK, 0 rows affected (0.82 sec)Insert some records in the table using insert command −mysql> insert into DemoTable660 values('2018-01-24'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable660 values('2019-07-10'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable660 values('2020-11-20'); Query OK, 1 row affected (0.59 sec)Display all records from the table using select statement −mysql> select *from DemoTable660;This will produce the ...
Read MoreMathematical Logical Terms and Definitions
TautologiesA Tautology is a formula which is always true for every value of its propositional variables.Example − Prove [ (A → B) ∧ A ] → B is a tautologyThe truth table is as follows −ABA → B(A → B) ∧ A[ (A → B) ∧ A ] → BTrueTrueTrueTrueTrueTrueFalseFalseFalseTrueFalseTrueTrueFalseTrueFalseFalseTrueFalseTrueAs we can see every value of [ (A → B) ∧ A ] → B is "True", it is a tautology.ContradictionsA Contradiction is a formula which is always false for every value of its propositional variables.Example − Prove (A ∨ B) ∧ [ ( ¬ A) ∧ (¬ B) ] ...
Read MoreHow to fetch a specific row when values are the same in MySQL?
To fetch a specific row when values are the same, use GROUP BY. Let us first create a table −mysql> create table DemoTable659(Id int, Name varchar(100), Score int); Query OK, 0 rows affected (0.52 sec)Insert some records in the table using insert command −mysql> insert into DemoTable659 values(11, 'John', 45); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable659 values(15, 'John', 59); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable659 values(15, 'Sam', 61); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select *from DemoTable659;This will produce the ...
Read MoreMathematical Logical Connectives
A Logical Connective is a symbol which is used to connect two or more propositional or predicate logics in such a manner that resultant logic depends only on the input logics and the meaning of the connective used.Generally there are five connectives which are −OR (∨)AND (∧)Negation/ NOT (¬)Implication / if-then (→)If and only if (⇔).OR (∨) − The OR operation of two propositions A and B (written as A ∨ B) is true if at least any of the propositional variable A or B is true.The truth table is as follows −ABA ∨ BTrueTrueTrueTrueFalseTrueFalseTrueTrueFalseFalseFalseAND (∧) − The AND operation ...
Read MoreHow to convert a MySQL TIME value to days and hours form?
Here, we are converting time value, for example 150:50:10 to days and hours form, i.e. 6 days 6 hours.You can use CONCAT() along with HOUR() for this. Let us first create a table −mysql> create table DemoTable657(DueTime time); Query OK, 0 rows affected (3.68 sec)Insert some records in the table using insert command. Here, we have inserted the records in the form of total hours −mysql> insert into DemoTable657 values('120:30:00'); Query OK, 1 row affected (0.38 sec) mysql> insert into DemoTable657 values('150:50:10'); Query OK, 1 row affected (0.27 sec)Display all records from the table using select statement −mysql> select *from ...
Read MoreKirchoff's Theorem
Kirchoff's theorem is useful in finding the number of spanning trees that can be formed from a connected graph.ExampleThe matrix 'A' be filled as, if there is an edge between two vertices, then it should be given as '1', else '0'.
Read MoreMySQL Stored procedure won't fetch the whole table?
You can use SELECT *FROM yourTableName in stored procedure. Let us first create a table −mysql> create table DemoTable654 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentFirstName varchar(100) ); Query OK, 0 rows affected (0.70 sec)Insert some records in the table using insert command −mysql> insert into DemoTable654(StudentFirstName) values('John'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable654(StudentFirstName) values('Sam'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable654(StudentFirstName) values('Mike'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable654(StudentFirstName) values('Robert'); Query OK, 1 row affected (0.12 sec)Display all records from the table using ...
Read MoreIsomorphism and Homeomorphism of graphs
IsomorphismIf two graphs G and H contain the same number of vertices connected in the same way, they are called isomorphic graphs (denoted by G ≅ H).It is easier to check non-isomorphism than isomorphism. If any of these following conditions occurs, then two graphs are non-isomorphic −The number of connected components are differentVertex-set cardinalities are differentEdge-set cardinalities are differentDegree sequences are differentExampleThe following graphs are isomorphic −HomomorphismA homomorphism from a graph G to a graph H is a mapping (May not be a bijective mapping) h: G → H such that − (x, y) ∈ E(G) → (h(x), h(y)) ∈ ...
Read MoreHow to change order of items in MySQL?
To change order of items in MySQL, use ORDER BY alias name. Let us first create a table −mysql> create table DemoTable653 (Product1Amount int, Product2Amount int); Query OK, 0 rows affected (0.42 sec)Insert some records in the table using insert command −mysql> insert into DemoTable653 values(400, 250); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable653 values(500, 300); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable653 values(40, 400); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable653 values(200, 450); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable653 values(50, 20); Query ...
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