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Articles by Chandu yadav
Page 60 of 81
Can we select second largest record from a table without using LIMIT clause in MySQL?
Yes, we can select second largest record from a table without using LIMIT clause. Let us first see an example and create a table −mysql> create table DemoTable ( Number int ); Query OK, 0 rows affected (0.66 sec)Insert records in the table using insert command −mysql> insert into DemoTable values(78); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(67); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable values(92); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(98); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(88); ...
Read MoreHow to update date of datetime field with MySQL?
Update date of datetime field with the help of arithmetic operator minus(-).The syntax is as followsupdate yourTableName set yourDateTimeColumnName=yourDateTimeColumnName - interval yourValue day where date(yourDateTimeColumnName)=’yourDateValue’;To understand the above syntax, let us create a table. The query to create a table is as followsmysql> create table updateDateDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ArrivalDate datetime -> ); Query OK, 0 rows affected (0.66 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into updateDateDemo(ArrivalDate) values('2011-01-13'); Query OK, 1 row affected (0.19 sec) mysql> insert into updateDateDemo(ArrivalDate) values('2013-04-21'); ...
Read MoreFinding highest value from sub-arrays in MongoDB documents?
To find the highest value from sub-arrays in documents, you can use an aggregate framework. Let us first create a collection with documents> db.findHighestValueDemo.insertOne( ... { ... _id: 10001, ... "StudentDetails": [ ... { "StudentName": "Chris", "StudentMathScore": 56}, ... { "StudentName": "Robert", "StudentMathScore":47 }, ... { "StudentName": "John", "StudentMathScore": 98 }] ... } ... ); { "acknowledged" : true, "insertedId" : 10001 } > db.findHighestValueDemo.insertOne( ... { ... _id: 10002, ... "StudentDetails": [ ...
Read MoreC program to write an image in PGM format
The PGM is the Portable Gray Map. If we want to store a 2d array in C as images in PNG, JPEG, or any other image format, we have to do lots of work to encode the data in some specified format before writing into a file.The Netpbm format gives an easy and portable solution. The Netpbm is an open source package of graphics program and it is used basically in linux or Unix platform. It also works under Microsoft Windows systems.Each file starts with a two-byte magic number. This magic number is used to identify the type of the ...
Read MoreMySQL Stored Procedure DEFINER=`root`@`%` is not working in localhost?
First of all, you need to check the host. The host can be ‘localhost’ or ‘%’. Check the existence of user accounts with host −mysql> select user, host from MySQL.user;This will produce the following output −+------------------+-----------+ | user | host | +------------------+-----------+ | Bob | % | | User2 | % | | mysql.infoschema | % | ...
Read MoreMySQL UPDATE query where id is highest AND field is equal to variable?
The syntax is as followsupdate yourTableName set yourColumnName1=yourValue where yourColumnName2=yourValue order by yourIdColumnName DESC LIMIT 1;To understand the above syntax, let us create a table. The query to create a table is as followsmysql> create table UpdateWithHighestDemo -> ( -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserStatus tinyint, -> UserRank int -> ); Query OK, 0 rows affected (0.61 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into UpdateWithHighestDemo(UserStatus, UserRank) values(1, 78); Query OK, 1 row affected (0.12 sec) mysql> insert into UpdateWithHighestDemo(UserStatus, UserRank) values(0, 118); Query ...
Read MoreHow to search for a date in MySQL timestamp field?
You can use DATE() function from MySQL for this. Let us first create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentAdmissionDate timestamp ); Query OK, 0 rows affected (0.63 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(StudentAdmissionDate) values('2011-01-12 12:34:43'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(StudentAdmissionDate) values('2012-10-23 11:32:21'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(StudentAdmissionDate) values('2001-02-14 05:12:01'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(StudentAdmissionDate) values('2018-12-31 15:10:04'); Query OK, 1 row affected (0.22 sec) mysql> ...
Read MoreSelecting Random Result from MySQL?
You need to use rand() function to select random result from MySQL.The syntax is as followsselect *from yourTableName order by rand() limit 1;To understand the above syntax, let us create a table. The query to create a table is as followsmysql> create table selectRandomRecord -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20) -> ); Query OK, 0 rows affected (0.53 sec)Insert some records in the table using insert command.The query is as followsmysql> insert into selectRandomRecord(StudentName) values('John'); Query OK, 1 row affected (0.17 sec) mysql> insert into selectRandomRecord(StudentName) values('Carol'); Query OK, ...
Read MoreWhy is iostream::eof inside a loop condition considered wrong?
The iostream::eof in a loop is considered as wrong because we haven’t reached the EOF. So it does not mean that the next read will succeed.When we want to read a file using file streams in C++. And when we use a loop to write in a file, if we check the end of file using stream.eof(), we are actually checking whether the file has reached end or not.Example Code#include #include using namespace std; int main() { ifstream myFile("myfile.txt"); string x; while(!myFile.eof()) { myFile >> ...
Read MoreHow to convert positive value to negative while inserting in MySQL?
Let us first create a tablemysql> create table recordsDemo -> ( -> UserId int, -> Value int -> ); Query OK, 0 rows affected (0.52 sec)Now insert some records in the table using insert command.The query is as followsmysql> insert into recordsDemo values(1, 10); Query OK, 1 row affected (0.17 sec) mysql> insert into recordsDemo values(3, 598); Query OK, 1 row affected (0.18 sec) mysql> insert into recordsDemo values(5, 786); Query OK, 1 row affected (0.25 sec) mysql> insert into recordsDemo values(7, 189); Query OK, 1 row affected (0.16 sec) mysql> insert into recordsDemo values(9, 345); ...
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