[IT 5-Minute Dictionary] Assignment #10

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• 30. Lessons from legacy systems from Corona
• 31. Data and best friend, SQL
• 32. What is NoSQL?
• 33. Git & GitHub, are they the same thing?
• 34. Is there a way to indicate the version?

Episode 30. Lessons from legacy systems from Corona

COBOL, common business oriented language

It was a popular language like Python at the time. In fact, 43% of the US banking system and 95% of the US ATM system are implemented in COBOL. Recently, in the aftermath of the coronavirus pandemic, the United States urgently needed to find COBOL developers who implemented support systems on government sites. Since it is not a currently popular language, the problem is that the community is small.

Therefore, we must make the program more responsible through the COBOL incident and always keep in mind that it must be constantly managed.

Episode 31. Data and its best friend, SQL

It is a structured query language that handles databases. A database only stores data and uses a DBMS database management system that has the ability to process data. SQL is a tool for communicating with DBMS to interact with databases. ex) MySQL, PostgreSQL, Oracle, MariaDB, etc.

Data is stored in table form, and data can be selected, inserted, deleted, etc. using SQL grammar. The SQL example is the same as the code below, which selects and outputs the email column from the users table.

select email from users;

Developers can use ORM with less dependence on SQL because it allows them to use SQL as a programming language. However, it is important to know the basics of SQL, so let's learn it.

Episode 32. What is NoSQL?

There is no good or bad in technology. You can use it according to its purpose, so make sure not to make the mistake of comparing and considering superiority.

document database

Mongo DB

Since data is stored in json document format, the configuration does not need to be the same for each database. In the case where the DBMS format is followed above, the DB has table-type data, so it is stored with one row added. However, the document format does not require rows containing all column values.

[
{ "id" : 1, "name" : "슬리퍼", "price" : 30000 },
{ "id" : 2, "name" : "바지", "price" : 50000 },
{ "price" : 10000 }
]

key value database

CassandraDB, DynamodB

CassandraDB has a wide column, and the speed of reading and writing a lot of data in an instant is fast. Netflix and Instagram are actually used because it is easy to process large amounts of data. DynamoDB is also fast, and is said to have been created by Amazon and used in an application called Duolingo.

graph database

It is a database needed for applications such as relationship networks and Facebook that require the concept of nodes.

Episode 33. Git & GitHub, are they the same thing?

Git enables version control, a tool that records code changes and allows you to revert to last month's code, for example, through version control. The advantage of using Git is that it becomes easier to collaborate with co-workers by editing and merging the parts each person is responsible for.

GitHub is a place where you can save and share all file history managed with Git. Like a file cloud service, even file history managed with Git can be shared. Uploading GitHub's Git history is called Push, and downloading it is called Pull. In addition to GitHub, there are Git history archives such as GitLab and Bitbucket.

Episode 34. Is there a way to indicate the version?

SemVer indicates the version with 3 numbers.

Semantic versioning, the first number indicates a major change, and the second number indicates a version update at the level of adding features. The last number indicates a version update, meaning a patch or bug fix.