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Articles on Trending Technologies
Technical articles with clear explanations and examples
Get the count of only unique rows in a MySQL column?
In MySQL, COUNT() will display the number of rows. DISTINCT is used to ignore duplicate rows and get the count of only unique rows.Let us first create a table:mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(10) ); Query OK, 0 rows affected (0.47 sec)Following is the query to insert some records in the table using insert command:mysql> insert into DemoTable(FirstName) values('Larry'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(FirstName) values('John'); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(FirstName) values('Sam'); Query OK, 1 row affected (0.13 sec) ...
Read MoreWhat's the difference between assignment operator and copy constructor in C++?
The Copy constructor and the assignment operators are used to initialize one object to another object. The main difference between them is that the copy constructor creates a separate memory block for the new object. But the assignment operator does not make new memory space. It uses reference variable to point to the previous memory block.Copy Constructor (Syntax)classname (const classname &obj) { // body of constructor }Assignment Operator (Syntax)classname Ob1, Ob2; Ob2 = Ob1;Let us see the detailed differences between Copy constructor and Assignment Operator.Copy ConstructorAssignment OperatorThe Copy constructor is basically an overloaded constructorAssignment operator is basically ...
Read MoreHow to retrieve a random row or multiple random rows in MySQL?
You can use RAND() method for this. To retrieve a random row, use the following syntaxSELECT *FROM yourTableName ORDER BY RAND() LIMIT yourIntegerNumber;To understand the above syntax, let us create a table. The query to create a table is as followsmysql> create table gettingRandomRow -> ( -> CustomerId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> CustomerName varchar(100) -> ); Query OK, 0 rows affected (0.45 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into gettingRandomRow(CustomerName) values('Chris'); Query OK, 1 row affected (0.14 sec) mysql> insert into gettingRandomRow(CustomerName) values('Robert'); ...
Read MoreHow to get the size of a column of a table using JDBC?
You can get the size of a column of a table using the getPrecision() method of the ResultSetMetaData class.//Retrieving the ResultSetMetaData object ResultSetMetaData rsmd = rs.getMetaData(); //getting the column type int size_name = rsmd. getPrecision(3);Assume we have a table named employee_data in the database with description as shown below:+----------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------+--------------+------+-----+---------+-------+ | id | int(11) | YES | | NULL | | | Name | varchar(255) | YES | ...
Read MoreWhat is Radio Group in android?
Before getting into example, we should know, What is radio group in android. Radio Group contains group of radio buttons. Using radio buttons we can select and un select according to user requirements.This example demonstrate about how to use radio group in android.Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. ...
Read MoreMySQL query to get sum of each column where every column has same number of values?
You can use aggregate function SUM() for this. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstValue int, SecondValue int, ThirdValue int ); Query OK, 0 rows affected (0.57 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(FirstValue, SecondValue, ThirdValue) values(10, 20, 30); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable(FirstValue, SecondValue, ThirdValue) values(60, 50, 40); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable(FirstValue, SecondValue, ThirdValue) values(80, 90, 100); Query OK, 1 row affected ...
Read MoreWhat is the difference between JspWriter and PrintWriter?
The JspWriter object contains most of the same methods as the java.io.PrintWriter class. However, JspWriter has some additional methods designed to deal with buffering. Unlike the PrintWriter object, JspWriter throws IOExceptions.
Read MoreHow to insert Date value into table in JDBC?
You can insert date values in SQL using the date datatype, The java.sql.Date class maps to the SQL DATE type.The PreparedStatement interface provides a method named setDate(). Using this you can insert date into a table. This method accepts two parameters −An integer representing the parameter index of the place holder (?) to which we need to set date value.a Date object representing the date value to be passed. The constructor of java.sql.Date class accepts a variable of long type representing the number of milliseconds from the epoch (standard base time I.e. January 1, 1970, 00:00:00 GMT).ExampleAssume we have created ...
Read MoreCan I use SUM() with IF() in MySQL?
Yes, you can use SUM() with IF() in MySQL. Let us first create a demo table:mysql> create table DemoTable ( Value int, Value2 int ); Query OK, 0 rows affected (0.51 sec)Following is the query to insert some records in the table using insert command:mysql> insert into DemoTable values(100, 400); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(100, 400); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values(400, 100); Query OK, 1 row affected (0.14 sec)Following is the query to display records from the table using select command:mysql> select *from DemoTable;This ...
Read More8086 program to add two 16-bit numbers with or without carry
In this program we will see how to add two 16-bit numbers with and without carry.Problem StatementWrite 8086 Assembly language program to add two 16-bit number stored in memory location 3000H – 3001H and 3002H – 3003H.Discussion8086 is 16-bit register. We can simply take the numbers from memory to AX and BX register, then add them using ADD instruction. When the Carry is present store carry into memory, otherwise only store AX into memory.We are taking two numbers BCAD + FE2D = 1BADAInput:AddressData……3000AD3001BC30022D3003FE…… Flow Diagram ProgramOutputAddressData……3004DA3005BA300601……
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