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Articles by Chandu yadav
Page 47 of 81
Android AsyncTask example and explanation
Android AsyncTask going to do background operation on background thread and update on main thread. In android we cant directly touch background thread to main thread in android development. asynctask help us to make communication between background thread to main thread.Methods of AsyncTaskonPreExecute() − Before doing background operation we should show something on screen like progressbar or any animation to user. we can directly comminicate background operation using on doInBackground() but for the best practice, we should call all asyncTask methods .doInBackground(Params) − In this method we have to do background operation on background thread. Operations in this method should ...
Read MoreC++ Program to Implement Queue using Linked List
A queue is an abstract data structure that contains a collection of elements. Queue implements the FIFO mechanism i.e the element that is inserted first is also deleted first. In other words, the least recently added element is removed first in a queue.A program that implements the queue using linked list is given as follows −Example#include using namespace std; struct node { int data; struct node *next; }; struct node* front = NULL; struct node* rear = NULL; struct node* temp; void Insert() { int val; coutdata = val; front = rear; ...
Read MoreHow to add 5 hours to current time in MySQL?
To add 5 hours in current time, we will use now() function from MySQL. The syntax is as follows −SELECT date_add(now(),interval some integer value hour);Now, I am applying the above query to add 5 hours to current time. The query is as follows −mysql> SELECT date_add(now(),interval 5 hour); The following is the output+---------------------------------+ | date_add(now(),interval 5 hour) | +---------------------------------+ | 2018-10-11 15:59:23 | +---------------------------------+ 1 row in set (0.00 sec)Look at the output above, it has increased the current time by 5 hours
Read MoreCan a number be used to name a MySQL table column?
Yes, we can include a number for column name in MySQL. We need to use the symbol backtick, which is as follows( ` `)To understand, we will make a table with the help of CREATE command. Let us create a table −mysql> CREATE table NumberColumnDemo -> ( -> `123` varchar(100) -> ); Query OK, 0 rows affected (0.51 sec)Above, I have created a column name as a number with the help of backtick symbol.Now, we can check the same by inserting records with the help of INSERT command. Let us insert a record, which is as follows −mysql> INSERT into ...
Read MoreHow to save time in milliseconds in MySQL?
To save time in milliseconds, we can use now(3) function because “milli 3” can be used for te same purpose. Firstly, I will create a table with the help of CREATE command −mysql> CREATE table MilliSecondDemo -> ( -> MyTimeInMillSec datetime(3) -> ); Query OK, 0 rows affected (0.70 sec)Inserting record into the table −mysql> INSERT into MilliSecondDemo values(now(3)); Query OK, 1 row affected (0.98 sec)Let us now view the table records −mysql> SELECT * from MilliSecondDemo; The following is the output+-------------------------+ | MyTimeInMillSec | +-------------------------+ | 2018-10-08 15:19:50.202 | +-------------------------+ 1 row in set (0.00 sec)
Read MoreHow do I get the current AUTO_INCREMENT value for a table in MySQL?
To know the current auto_increment value, we can use the last_insert_id() function. Firstly, we will create a table with the help of INSERT command.Creating a table −mysql> CREATE table AutoIncrement -> ( -> IdAuto int auto_increment, -> primary key(IdAuto) -> ); Query OK, 0 rows affected (0.59 sec)After creating a table, we will insert the records with the help of INSERT command. Inserting records −mysql> INSERT into AutoIncrement values(); Query OK, 1 row affected (0.48 sec) mysql> INSERT into AutoIncrement values(); Query OK, 1 row affected (0.17 sec) mysql> INSERT into AutoIncrement values(); Query OK, 1 row affected ...
Read MoreSELECT DISTINCT vs GROUP BY in MySQL?
SELECT DISTINCT can be used to give distinct values. Use it to remove duplicate records and it can be used with aggregate function as well. For example: MAX, AVG etc. This can be applied on a single column.Now, I am creating a table to use SELECT DISTINCT for a column. Creating a table with the help of CREATE command −mysql> CREATE TABLE DistinctDemo -> ( -> id int, -> name varchar(100) -> ); Query OK, 0 rows affected (0.64 sec)Inserting records −mysql> INSERT into DistinctDemo values(1, 'John'); Query OK, 1 row affected (0.17 sec) mysql> INSERT into DistinctDemo values(2, ...
Read MoreFind records from one MySQL table which don't exist in another?
To find the records from one MySQL table which don’t exist in another table we can use the subquery for the table which does not have the records. This can be better understood using the given steps −First a table is created using the create command. The table name is ‘PresentHistory’ and it has two columns. This is given as follows −mysql> CREATE table PresentHistory -> ( -> HisID int, -> HisName varchar(100) -> ); Query OK, 0 rows affected (0.54 sec)After creating the table, some records are inserted that will be present in the second table as well. This ...
Read MoreHow can I stop running a MySQL query?
Before stopping a running query of MySQL, first we need to see how many processes are running with the help of show command.The query for that is given as follows −mysql> show processlist;After executing the above query, we will get the output with some id’s. This is given as follows −+----+-----------------+-----------------+----------+---------+-------+------------------------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+-----------------+-----------------+----------+---------+-------+------------------------+------------------+ | 4 | event_scheduler | localhost | NULL | Daemon | 71034 | Waiting on empty queue | NULL | | 8 | Manish | localhost:53496 | business | Query | ...
Read MoreHow to check if a MySQL database exists?
The schema_name command is used to check if a MySQL database exists or not. The syntax of this command is as follows −select schema_name from information_schema.schemata where schema_name = 'database name';Now, the above command is used to check whether the database exists or not. The query for that is as follows −Case 1 − The database exists.mysql> select schema_name from information_schema.schemata where schema_name = 'business'; The output obtained is as follows −+-------------+ | SCHEMA_NAME | +-------------+ | business | +-------------+ 1 row in set (0.00 sec)Case 2 − The database does not exist.mysql> select schema_name from information_schema.schemata ...
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