Hierarchical Data Model In the Hierarchical data model, the relationship between the table and data is defined in parent-child structure. In this structure, data is arranged in the form of a tree structure. This model supports one-to-one and one-to-many relationships. Network Model The Network model arranges data in a graph structure. In this model, each parent can have multiple children, and children can also have multiple parents. This model supports many-to-many relationships as well. Comparison Table ... Read More

In Relational database tables are associated with each other and we used foreign key to maintain relationships between tables. We used join clause to retrieve data from associated tables. The join condition indicates how column in each table are matched against each other. There are two types of joins clause in SQL Inner join Outer joinOuter join is again divided into parts −LEFT OUTER JOIN - It will return all data of the left table and matched  records in both table RIGHT OUTER JOIN - it will return all the data of the right table and matched records in both tableSr. No.KeyInner joinOuter join1Basic It ... Read More

Both the TRUNCATE statement and the DELETE statement are included in the category of SQL queries for deleting the data stored in a table. They carry out deletion operations on records or rows of a table that are no longer needed. A condition is applied before each entry in the table that is being deleted when using the DELETE command. To put it another way, it is possible to delete one or more rows all at once. However, with the TRUNCATE command, each row is removed from the table simultaneously. When we delete something using the DELETE query, a log ... Read More

An Index is a lookup table associated with an actual table or View that is used by the database to improve the data retrieval performance timing. In an index,  keys are stored in a structure (B-tree) that enables SQL Server to find the rows associated with the key values quickly and efficiently. Index gets created automatically if the primary key and unique key constraints are defined on the table. There are two types of index namely, Clustered Index and Non-Clustered Index. Read this article to learn more about clustered index and non-clustered index and how they are different from each ... Read More

ETL stands for Extract, Transform and Load. ETL tool is used to extract data from the source RDBMS database and transform extracted data such as applying business logic and  calculation, etc. and  then load data into the target data warehouse. In ETL tool,  transformation of the data performed at the ETL server. It is used for low amount data.ELT stands for Extract, Load and Transform. ELT tool is also used to extract data from source database and then load data into target database without transformation. In ELT, transformation of data is performed at the target database. In general, in an ... Read More

In this article, we will learn how to change the MySQL Data Directory or relocate the MySQL Database data to the new location, this situation may be used when the database is growing very fast, or for some security reasons we want to move the data directory to the new location.PrerequisitesAn Ubuntu machine with a non-root user with Sudo permission.MySQL installed and working.A new volume or location where we want to move the database data location, the new location will be /mnt/data_vol/MySQL as the data_vol is the new volume attached to the machine or server.Changing the MySQL Data Folder LocationBefore ... Read More

There are two ways of organizing data in a DBMS − one is row-oriented database and another is column-oriented database. The basic difference between the two is that a row-oriented database stores the data tables by rows, whereas a column-oriented database stores the data tables by columns. Read this article to learn more about row-oriented database and column-oriented database and how they are different from each other. What is Row-Oriented Database? A Roworiented database is a traditional database like Oracle, MySQL, etc. It stores data tables by rows and the common method of storing a table is to serialize each ... Read More

In this tutorial, I will be explaining about – how to set up a secure connection to MySQL server using an SSH connection for encryption so that data in the database will be in safe and which is impossible for hackers to steal the data. SSL is used to verify the means of SSL certificates which can protect against phishing attacks. This will also show you – how to enable SSL on MySQL server also.Enabling SSL SupportConnect to the MySQL server and check that SSL status of the MySQL server# mysql -u root -p mysql> show variables like '%ssl%'; Output: ... Read More

What is NoSQL?As per the official Wiki definition: “A NoSQL (originally referring to “non SQL” or “non relational”) database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relation databases (RDBMS). It encompasses a wide variety of different database technologies that were developed in response to a rise in the volume of data stored about users, objects and products, the frequency in which this data is accessed, and performance and processing needs. Generally, NoSQL databases are structured in a key-value pair, graph database, document-oriented or column-oriented structure.Over decades ... Read More

With so many databases in the market, the mind wars have begun and it is the right time to understand the difference and importance of top 3 relational databases in the market – Microsoft SQL Server, Oracle PL/SQL, and MySQL. The relational database management systems have currently become the backbone of the industry and with so many options available, it is difficult to figure out which one to choose.The relational database management systems was introduced in 1980’s. This article is focussing on exploring the history and features of three popular RDBMS in the industry: Microsoft SQL Server, Oracle, and MySQL. ... Read More