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To merge selects together, you need to use GROUP BY clause. To understand the concept, let us create a table. The query to create a table is as follows −mysql> create table MergingSelectDemo -> ( -> RoomServicesId int, -> RoomId int, -> ServiceId int -> ); Query OK, 0 rows affected (1.98 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into MergingSelectDemo values(10, 10, 10); Query OK, 1 row affected (0.29 sec) mysql> insert into MergingSelectDemo values(20, 10, 20); Query OK, 1 row affected ... Read More
Yes, it is possible to calculate a correlation in a query. To understand the correlation in a query, you need to first create a table. The query to create a table is as followsmysql> create table correlationDemo - > ( - > value float not null, - > value2 float not null - > ); Query OK, 0 rows affected (0.62 sec)Insert some records in the table with the help of insert command. The query is as follows to insert records in the tablemysql> insert into correlationDemo values(1, ... Read More
You can use hex2bin() function since it is the PHP equivalent of MySQL's UNHEX().The syntax is as follows −$anyVariableName = hex2bin("yourHexadecimalValue");To understand the above syntax, let us implement the above syntax in PHP. The PHP code is as follows −$myFirstValue = hex2bin("7777772E4D7953514C4578616D706C652E636F6D"); var_dump($myFirstValue); $mySecondValue=hex2bin("416476616E6365644A617661576974684672616D65776F726B"); echo(''); var_dump($mySecondValue);The snapshot of PHP code is as follows −Here is the snapshot of The output −Here is the MySQL UNHEX() −Case 1 − The query is as follows −mysql> SELECT UNHEX("7777772E4D7953514C4578616D706C652E636F6D");The following is The output −+---------------------------------------------------+ | UNHEX("7777772E4D7953514C4578616D706C652E636F6D") | +---------------------------------------------------+ | www.MySQLExample.com ... Read More
To copy data from one field to another on every row, use the UPDATE command.Let us first create a table −mysql> create table DemoTable ( StudentId int, StudentFirstName varchar(20), StudentMarks int default 0 ); Query OK, 0 rows affected (0.49 sec)Following is the query to insert records in the table using insert command −mysql> insert into DemoTable(StudentId, StudentFirstName) values(89, 'Larry'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable(StudentId, StudentFirstName) values(35, 'Robert'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(StudentId, StudentFirstName) values(48, 'Chris'); Query OK, 1 row affected (0.13 sec) ... Read More
Weakly or Strongly Connected for a given a undirected graph can be found out using DFS. This is a C++ program of this problem.Functions usedBegin Function fillorder() = fill stack with all the vertices. a) Mark the current node as visited and print it b) Recur for all the vertices adjacent to this vertex c) All vertices reachable from v are processed by now, push v to Stack End Begin Function DFS() : a) Mark the current node as visited and print it b) Recur for all the vertices adjacent to this vertex EndExample#include ... Read More
To set column values as column names in the query result, you need to use a CASE statement.The syntax is as follows −select yourIdColumnName, max(case when (yourColumnName1='yourValue1') then yourColumnName2 else NULL end) as 'yourValue1', max(case when (yourColumnName1='yourValue2') then yourColumnName2 else NULL end) as 'yourValue2', max(case when yourColumnName1='yourValue3') then yourColumnName2 else NULL end) as 'yourValue3’, . . N from valueAsColumn group by yourIdColumnName order by yourIdColumnName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table valueAsColumn -> ( -> UserId int, -> UserColumn1 varchar(10), -> ... Read More
A bind variable is an SQL statement with a temporary variable as place holders which are later replaced with appropriate values. For example, if you have a table named employee in the database created as shown below:+---------+--------+----------------+ | Name | Salary | Location | +---------+--------+----------------+ | Amit | 30000 | Hyderabad | | Kalyan | 40000 | Vishakhapatnam | | Renuka | 50000 | Delhi | | Archana | ... Read More
You can add/set an auto increment constraint to a column in a table using the ALTER TABLE command.SyntaxALTER TABLE table_name ADD id INT PRIMARY KEY AUTO_INCREMENTAssume we have a table named Dispatches in the database with 7 columns namely id, CustomerName, DispatchDate, DeliveryTime, Price and, Location with description as shown below:+--------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +--------------+--------------+------+-----+---------+-------+ | ProductName | varchar(255) | YES | UNI | NULL | | | CustomerName | varchar(255) | YES | ... Read More
There is no equivalent of ROW_NUMBER() in MySQL for inserting but you can achieve this with the help of variable. The syntax is as follows −SELECT (@yourVariableName:=@yourVariableName + 1) AS `anyAliasName`, yourColumnName1, yourColumnName2, ...N FROM yourTableName ,(SELECT @yourVariableName:=0) AS anyAliasName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table RowNumberDemo -> ( -> UserId int, -> UserName varchar(20) -> ); Query OK, 0 rows affected (0.74 sec)Insert some records in the table using insert command. The ... Read More
You can use UNION to get the previous and next record in MySQL.The syntax is as follows(select *from yourTableName WHERE yourIdColumnName > yourValue ORDER BY yourIdColumnName ASC LIMIT 1) UNION (select *from yourTableName WHERE yourIdColumnName < yourValue ORDER BY yourIdColumnName DESC LIMIT 1);To understand the concept, let us create a table. The query to create a table is as followsmysql> create table previousAndNextRecordDemo - > ( - > Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > Name varchar(30) - > ); Query OK, 0 rows affected (1.04 ... Read More