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Technical articles with clear explanations and examples
When are two tables connected with MySQL FOREIGN KEY then how can we say that the integrity of data is maintained in child table?
Actually, foreign keys enforce referential integrity that helps us to maintain the consistency and integrity of the data automatically. It can be understood with the example of two tables named ‘customer’ and ‘orders’. Here, ‘customer’ is the parent table and ‘orders’ is the child table. We cannot create an order for a non-existent customer. It can be demonstrated by inserting the values in both the tables as follows −mysql> Select * from Customer; +----+--------+ | id | name | +----+--------+ | 1 | Gaurav | | 2 | Raman | | 3 | Harshit| | 4 | Aarav | ...
Read MoreIn case of FOREIGN KEY constraint, what kind of relationship is there between MySQL parent and child tables?
The relationship between parent and child table is One-to-Many relationship. It can be understood with the example of two tables named ‘customer’ and ‘orders’. Here, ‘customer’ is the parent table and ‘orders’ is the child table. The relationship is one-to—many because a customer can have more than one order. It can be demonstrated by inserting the values in both the tables as follows −mysql> Select * from Customer; +----+---------+ | id | name | +----+---------+ | 1 | Gaurav | | 2 | Raman | | 3 | Harshit | | 4 | Aarav | +----+---------+ ...
Read MoreHow can we drop UNIQUE constraint from a MySQL table?
For dropping UNIQUE constraint from a MySQL table, first of all, we must have to check the name of the index created by the UNIQUE constraint on the table. As we know that SHOW INDEX statement is used for this purpose. The ‘key_name’ in the result set of SHOW INDEX statement contains the name of the index. Now either with the help of DROP INDEX statement or ALTER TABLE statement, we can drop the UNIQUE constraint. The syntax for both the statements is as follows −SyntaxDROP INDEX index_name ON table_name; OR ALTER TABLE table_name DROP INDEX index_name;ExampleSuppose we have the ...
Read MoreHow can we create multicolumn UNIQUE indexes?
For creating multicolumn UNIQUE indexes we need to specify an index name on more than one column. Following example will create a multicolumn index named ‘id_fname_lname’ on the columns ‘empid’, ’first_name’, ’last_name’ of ‘employee’ table −mysql> Create UNIQUE INDEX id_fname_lname on employee(empid, first_name, last_name); Query OK, 0 rows affected (0.41 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> describe employee; +------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +------------+-------------+------+-----+---------+-------+ | empid | int(11) | YES | MUL | NULL | | | first_name | varchar(20) | YES | | NULL | | | ...
Read MoreIn SAP database, Importing table columns with /'s in the name
I would suggest you to use BCP utility to perform an import/export of data to a text file in SQL Server. When you run below command, it loads data to a text file.BCP Db.TN out "Location of the text file " -c -S ServerName –TNow if you want to load data to SQL Server from a flat file, you can use this:BCP Db.TN in "Location of the text file " -c -S ServerName –TYou can also try editing Mappings while loading data from a flat file.
Read MoreImporting data from Pgsql to SAP HANA database
Import and Export using a flat file is the easiest option. You can use CSV file if it is a onetime activity. However, If you think it is a repetitive activity then I would suggest you use HANA ETL options like HANA SLT replication, Smart Data access, etc.SAP HANA Replication allows migration of data from source systems to SAP HANA database. Simple way to move data from existing SAP system to HANA is by using various data replication techniques.System replication can be set up on the console via command line or by using HANA studio. The primary ECC or transaction ...
Read MoreRunning a SQL query from specific month in SAP DB
When your T0.name is char filed, you should replace Order By as below −order by case when cast(left (T0.Name,2) as int)>=8 then cast(left (T0.Name,2) as int)-8 else cast(left (T0.Name,2) as int)+4 end
Read MoreHow to add picasso library in android studio?
Before getting into picasso library example, we should know about picasso. Picasso is image processing library and developed by Square Inc. In older days we used to write lengthy of codes to grab image from server or do process., to optimize the process picasso introduced.This example demonstrate about how to integrate picasso library in android studio.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 in build.gradle.apply plugin: 'com.android.application' android { compileSdkVersion 28 defaultConfig { ...
Read MoreHow to Install and Configure an NTP Client and Server on Linux?
This article will help to know how to configure an NTP (Network Time Protocol) server and client on RHEL/Cent OS Linux to manage the system clock with to help of an NTP server.NTP (Network Time Protocol)NPT is used to synchronize a computer’s machine’s time with another time source. In RHEL / CentOS Linux we can use NTP or OpenNTPD server, which provides client and server software for time synchronization.Installing NTP SoftwareThe NTP package have utilities and daemons that will synchronize the machine time to Coordinated Universal Time (UTC) via the NTP protocol. The NTP package has ntpdate (Which updates the ...
Read MoreHow to Install a Software on Linux Using Yum Command?
In this article, we will learn about “how to use the Yum command” for installing the packages. Also note that, the repositories on the Cent OS 6.7 YUM (Yellowdog Update Modified) is a tool used to develop by Redhat. You can use this materials for learning the YUM.Managing Software with YUMUse the yum utility to install or modify the software on your system in the following ways –New software installation from repositories.Installing software from an individual package file.Updating the existing software on your system.Removing unwanted software from your system.Installing Software from a Package FileThe yum commands used in this is ...
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