You can use DELETE command with some condition for this since we need to keep one record and delete rest of the duplicate records.Let us first create a table −mysql> create table DemoTable (    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,    StudentName varchar(40) ); Query OK, 0 rows ... Read More

Heap OverflowHeap is used to store dynamic variables. It is a region of process’s memory. malloc(), calloc(), resize() all these inbuilt functions are generally used to store dynamic variables.Heap overflow occurs when −A) If we allocate dynamic large number of variables −int main() {    float *ptr = (int *)malloc(sizeof(float)*1000000.0)); ... Read More

First, create a HashMap, which is to be iterated −Mapmap = new LinkedHashMap(); map.put("Jack", "0"); map.put("Tim", "1"); map.put("David", "2"); map.put("Tom", "3"); map.put("Kevin", "4");Now, use Iterator to map through keyset −Iterator iterator = map.keySet().iterator();Iterate through all the pairs −while (iterator.hasNext()) {    String resKey = (String) iterator.next();    System.out.println("Rank of " ... Read More

Let us first create a table. Here, we have set UserId as AUTO_INCREMENT PRIMARY KEY −mysql> create table DemoTable (    UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY ); Query OK, 0 rows affected (0.72 sec)Following is the query to set int column to auto increment by 1 beginning at ... Read More

Before getting into the example, we should know what PriorityBlockingQueue is. It is an unbounded queue and follows the same order as a priority queue. The main usage of priority blocking queue is, it going to handle out of memory error.This example demonstrates about How to use poll() in android ... Read More

You can use CASE statement with UPDATE command for this. Let us first create a table −mysql> create table DemoTable (    Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,    Value int ); Query OK, 0 rows affected (1.44 sec)Insert records in the table using insert command −mysql> insert into DemoTable(Value) ... Read More

Let’s say the following is our Map with unsorted keys −HashMapmap = new HashMap(); map.put("1", "A"); map.put("6", "B"); map.put("3", "C"); map.put("7", "D"); map.put("5", "E"); map.put("2", "F"); map.put("4", "G"); map.put("8", "H");Now, sort the above Map. The result of tMap below would be a sorted map by key −MaptMap = new TreeMap(map);Example Live ... Read More

Before getting into an example, we should know what ConcurrentLinkedDeque is, it is unbounded deque based on linked nodes. Multiple threads can access deque elements with safety.This example demonstrates about How to use pollLast() in android ConcurrentLinkedDequeStep 1 − Create a new project in Android Studio, go to File ⇒ ... Read More

You can use INFORMATION_SCHEMA.COLUMNS to check if a database is empty or not. The syntax is as follows −SELECT COUNT(DISTINCT `TABLE_NAME`) AS anyAliasName FROM `INFORMATION_SCHEMA`.`COLUMNS` WHERE `table_schema` = 'yourDatabaseName';The above syntax returns 0 if the database has notable otherwise it returns the number of tables. For our example, we are ... Read More

Let’s say we have the following SortedSet −SortedSet set = new TreeSet(); set.add("T"); set.add("R"); set.add("S"); set.add("Q"); set.add("V"); set.add("U"); set.add("W");Now, after displaying the above elements with Iterator, you can insert values like this to a SortedSetset.add("Z"); set.add("Y");Example Live Demoimport java.util.Iterator; import java.util.SortedSet; import java.util.TreeSet; public class Demo {    public static void ... Read More