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Articles on Trending Technologies
Technical articles with clear explanations and examples
Perform custom sorting in MySQL
To perform custom sorting in MySQL, use ORDER BY FIELD(). Let us first create a table −mysql> create table DemoTable -> ( -> Id int -> ); Query OK, 0 rows affected (0.82 sec)Insert some records in the table using insert command:mysql> insert into DemoTable values(101); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(103); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable values(102); Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable values(105); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement ...
Read MoreConcatenate the column values with separate text in MySQL and display in a single column
Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.93 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(101, 'Chris'); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable values(102, 'David'); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values(103, 'Robert'); Query OK, 1 row affected (0.16 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output−+------+--------+ | Id | Name ...
Read MoreUpdate MySQL column based on email address?
Let us first create a table −mysql> create table DemoTable -> ( -> EmailAddress varchar(20), -> Score int -> ); Query OK, 0 rows affected (1.05 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('Chris@gmail.com', 67); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values('Robert@gmail.com', 57); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('David@gmail.com', 98); Query OK, 1 row affected (0.14 sec)Display all records from the table using select statement −mysql> select *from DemoTable;This will produce the following output −+------------------+-------+ | EmailAddress ...
Read MoreHow to update MySQL table storage engine
To update MySQL table engine, following the below syntax −Syntaxalter table yourTableName ENGINE=InnoDB;Let us first create a table −mysql> create table DemoTable -> ( -> StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentName varchar(20), -> StudentAge int, -> StudentCountryName varchar(20) -> )ENGINE=MyISAM, AUTO_INCREMENT=101; Query OK, 0 rows affected (0.18 sec)Let us check the description of table −mysql> show create table DemoTable;This will produce the following output −+---------------+-----------------------------------------------------------------------------------------+ | Table | Create Table ...
Read MoreFetch maximum individual marks for a student with marks1 and marks2 records in MySQL?
For this, use MAX() along with GROUP BY clause. Let us first create a table −mysql> create table DemoTable -> ( -> StudentEmailId varchar(20), -> Marks1 int, -> Marks2 int -> ); Query OK, 0 rows affected (0.90 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John@gmail.com', 45, 32); Query OK, 1 row affected (0.30 sec) mysql> insert into DemoTable values('John@gmail.com', 32, 45); Query OK, 1 row affected (0.34 sec) mysql> insert into DemoTable values('Carol@gmail.com', 32, 45); Query OK, 1 row affected (1.64 sec) mysql> insert into DemoTable values('David@gmail.com', 45, 32); ...
Read MoreSelect the maximum for each value in a MySQL table?
For this, use GROUP BY clause along with MAX(). Let us first create a table −mysql> create table DemoTable -> ( -> CountryName varchar(20), -> Population int -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('US', 560); Query OK, 1 row affected (0.23 sec) mysql> insert into DemoTable values('UK', 10090); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('UK', 8794); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values('US', 1090); Query OK, 1 row affected (0.21 sec)Display ...
Read MoreDoes grant on *.* apply to databases created after the grant in MySQL?
Yes, since this is a global privilege. Let us first create a user −mysql> CREATE USER 'Jace'@'localhost' IDENTIFIED BY 'Jace123'; Query OK, 0 rows affected (0.67 sec)Here is the query to grant for global privileges with *.*:mysql> GRANT SELECT ON *.* TO 'Jace'@'localhost'; Query OK, 0 rows affected (0.58 sec)Now you can show all grants for a user −mysql> show grants for 'Jace'@'localhost';This will produce the following output −+-------------------------------------------+ | Grants for Jace@localhost | +-------------------------------------------+ | GRANT SELECT ON *.* TO `Jace`@`localhost` | +-------------------------------------------+ 1 row in set (0.14 sec)
Read MoreFind the node whose absolute difference with X gives maximum value in C++
Suppose we have a tree, and the weights of all the nodes and an integer x. We have to find the node i, such that |weight[i] - x| is minimum. If the graph is like below, and x = 15Output will be 3. Now for different nodes, it will be like belowNode 1, |5 – 15| = 10Node 2, |10 – 15| = 5Node 3, |11 – 15| = 4Node 4, |8 – 15| = 7Node 5, |6 – 15| = 9The idea is simple. We will perform the DFS on the tree, and keep track of the node, whose ...
Read MoreMySQL query to sort by both timestamp and enum?
For this, you can use ORDER BY DATE(). Let us first create a table. Here, we have a column with type DATE and another with type ENUM −mysql> create table DemoTable -> ( -> JoiningDate date, -> Status ENUM('Good', 'Excellent', 'Bad') -> ); Query OK, 0 rows affected (0.58 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('2019-01-21', 'Excellent'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Status) values('Bad'); Query OK, 1 row affected (0.17 sec) mysql> insert into DemoTable(Status) values('Good'); Query OK, 1 row affected (0.13 sec)Display all ...
Read MoreHow to use a select statement while updating in MySQL?
For this, use sub query along with WHERE clause while using the MySQL UPDATE command. Let us first create a table −mysql> create table DemoTable -> ( -> Id int, -> Name varchar(20) -> ); Query OK, 0 rows affected (0.82 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100, 'Chris'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable values(250, 'David'); Query OK, 1 row affected (0.25 sec) mysql> insert into DemoTable values(150, 'Mike'); Query OK, 1 row affected (0.12 sec)Display all records from the table using select ...
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