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Articles by Anvi Jain
Page 21 of 43
How to create a table with auto-increment column in MySQL using JDBC?
While creating a table, in certain scenarios, we need values to column such as ID, to be generated/incremented automatically. Various databases support this feature in different ways.In MySQL database you can declare a column auto increment using the following syntax.CREATE TABLE table_name( ID INT PRIMARY KEY AUTO_INCREMENT, column_name1 data_type1, column_name2 data_type2, column_name3 data_type3, column_name4 data_type4, ............ ........... );MySQL query to create a table with auto-incremented column.CREATE TABLE Sales( ID INT PRIMARY KEY AUTO_INCREMENT, ProductName VARCHAR (20) NOT NULL, CustomerName VARCHAR (20) NOT NULL, DispatchDate date, DeliveryTime timestamp, Price ...
Read MoreAvoid placing password on command line with MySQL Utilities?
First you need to reach the location of “my.cnf” with the help of below query for MySQL Utilities. The query is as follows −mysql> select @@datadir;The following is the output that display where “my.conf” is −+---------------------------------------------+ | @@datadir | +---------------------------------------------+ | C:\ProgramData\MySQL\MySQL Server 8.0\Data\ | +---------------------------------------------+ 1 row in set (0.00 sec)Follow the above path in order to open the “my.cnf” file. The snapshot of “my.cnf” location is as follows −Now you can put the below MySQL Utilities in my.cnf which is as ...
Read MoreSimple way to toggle a value of an int field in MySQL
To toggle a value of an int field, you can use update command with if(). The syntax is as follows −update yourTableName set yourColumnName = IF(yourColumnName = 0, 1, 0);To understand the above toggle syntax, create a table with some int value. The query to create a table is as follows −mysql> create table ToggleDemo −> ( −> IsOnOrOff int −> ); Query OK, 0 rows affected (0.53 sec)Let us insert int values in the table with the help of insert command. The query is as follows −mysql> insert into ToggleDemo values(1); Query OK, 1 ...
Read MoreBuilt-in objects in Python (builtins)
The builtins module is automatically loaded every time Python interpreter starts, either as a top level execution environment or as interactive session. The Object class, which happens to be the base class for all Python objects, is defined in this module. All built-in data type classes such as numbers, string, list etc are defined in this module. The BaseException class, as well as all built-in exceptions, are also defined in it. Further, all built-in functions are also defined in the built-ins module.Since this module is imported in the current session automatically, normally it is not imported explicitly. All the built-in ...
Read MoreHow can I develop for iPhone using a Windows development machine?
Generally iOS applications can be developed on mac operating systems only, but recently with system development now applications for iOS can partially be developed on windows system too.To develop iOS or any other apps for apple platform, we need Xcode which is a native Apple software and can be installed on mac operating systems only. Also, a mac operating system is generally installed and supported on an Apple device.There are multiple work around for this like buying a normal laptop installing third party software to run mac OS on them and later installing Xcode, or buying/renting a cloud Mac. In ...
Read MoreSet up a simple delegate to communicate between two view controllers in iPhone
In this article, you learn about delegates and creating delegates. First of all, What’s a delegate?Delegate is a simple term that refers to communication between objects. It is a simple way of connecting objects and communication between them.How does delegate work?A delegate is created with help of protocol. A protocol is declared in class, inside which some event will happen, that should notify other classes. In protocol we write the declaration of function and it is defined inside the calling class.How to create a delegate?We’ll do this with help of an example project.Steps to perform −Create a class, name it ...
Read MoreHow add unique key to existing table (with non-unique rows)?
You can add unique key to existing table with the help of alter command. The syntax is as follows −ALTER TABLE yourTableName ADD CONSTRAINT yourConstraintName UNIQUE(yourColumnName1, yourColumnName2, ............N);To understand the above concept, let us create a table with some columns. The query to create a table −mysql> create table MovieCollectionDemo −> ( −> MovieId int, −> MovieDirectorName varchar(200), −> NumberOfSongs int unsigned −> ); Query OK, 0 rows affected (0.62 sec)Now you can check the table does not have any unique constraint. The query to check unique constraint is ...
Read MoreWhy is it faster to process a sorted array than an unsorted array in C++?
In C++, it is faster to process a sorted array than an unsorted array because of branch prediction. In computer architecture, a branch prediction determines whether a conditional branch (jump) in the instruction flow of a program is likely to be taken or not.Let’s take an example −if(arr[i] > 50) { Do some operation B } else { Do some operation A }If we run this code for 100 elements in unsorted and sorted order below things will be happened −For sorted array −1, 2, 3, 4, 5, …… 50, 51………100 A, A, A, A, A A, B ...
Read MoreHow can we get the summary output of a column in MySQL result set itself?
We can get the summary output of a column in MySQL result set by using the “WITH ROLLUP” modifier. This modifier is used with GROUP BY CLAUSE. It gives the summary output to include extra rows that represent higher-level summary operations.ExampleIn this example, the WITH ROLLUP modifier gave the summary output with total cost value in the extra row.mysql> Select Item_name, SUM(Cost) AS Total_cost from Item_list GROUP BY Item_name WITH ROLLUP; +-----------+------------+ | Item_name | Total_cost | +-----------+------------+ | Notebook | 45.00 | | Pen | 31.70 | | Pencilbox | 125.20 | | NULL | 201.90 | +-----------+------------+ 4 rows in set (0.00 sec)
Read MoreCreate a MySQL stored procedure which fetches the rows from a table by using a cursor?
Following is a stored procedure which fetches the records from name column of table ‘student_info’ having the following data −mysql> Select * from Student_info; +-----+---------+------------+------------+ | id | Name | Address | Subject | +-----+---------+------------+------------+ | 101 | YashPal | Amritsar | History | | 105 | Gaurav | Chandigarh | Literature | | 125 | Raman | Shimla | Computers | | 127 | Ram | Jhansi | ...
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