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1 Name three applications you have used that employed a database system to store and access persistent data. (e.g. airlines, online trade, banking, university system)

1.1 Chase bank app

It uses a database system to manage the users’ account information, including their profiles, balance, bank transactions, etc. It also provides monthly spending summaries based on its database.

1.2 Amazon shopping app

Amazon uses a database system to store all the product information, the customers’ orders, account information. They also utilize the customers’ purchase and search history stored in the database to make product recommendations.

1.3 Outlook email online/app

It uses a database system to store the user information, all emails received and sent, and users’ contacts.

2 Propose three applications in social science or policy science projects. Be sure you include:

2.1 Research Method app

The app is aimed to provide method instructions for users when they are doing research.

There will be several options: The first section contains a whole list of qualitative and quantitative research methods by category and with detailed descriptions, examples, related R or Python packages, and functions to accomplish if there are. The second section has the search function; users could input the keyword to search the method.

2.2 Political Science Student Information Sharing app

The app aims to provide a platform for students from different universities majoring in political science to share study and daily information, make friends, and talk about their career paths.

There will be four different communities for the students at different education levels: undergraduate student, master student, Ph.D. student, and Postdoc.
When the users have registered with their information and education, they will be divided into the same level community. For each community, there will be several modules: Life, Study, Career, etc.

2.3 Social Science Second Book app

This app aims to build a platform for social science students to sell their used books once they don’t need them and purchase from others at a relatively low price compared to buying the new ones from the book store.

3 If data can be retrieved efficiently and effectively, why data mining is needed?

The data stored in SQL databases are well-structured and can be retrieved efficiently and effectively. But the unstructured data produced by multiple social media platforms stored in NoSQL databases could not be retrieved with high efficiency; thus, data mining is needed to discover the tendency and correlation between the complex data.

4 Why NoSQL systems emerged in the 2000s, and briefly contrast their features with traditional database systems.

With the rapid development of social media, there are many data about connections between people and the posted data created. These data do not fit into the traditional structured databases (Silberschatz et al. 2019, pp. 28-29). Thus, the NoSQL systems are emerging.

SQL databases are mainly relational databases (RDBMS). They apply an aged technology with a history of nearly 50 years. SQL databases are table-based in rows & columns and must strictly adhere to standard schema definitions. They are a better option for applications that need multi-row transactions. And they have a well-designed pre-defined schema for structured data.

In contrast, NoSQL databases are mainly non-relational or distributed databases, which apply relatively young technology. NoSQL databases can be based on documents, key-value pairs, graphs, or columns, and they don’t have to stick to standard schema definitions. They have a dynamic schema for unstructured data. So data can be flexibly stored without having a pre-defined structure.

5 What are the things current database system cannot do?

I guess they could not store all types of unstructured and unprocessed data. At least not easy for peopel to retrieve to analyze.

6 Describe at least three tables that might be used to store information in a social- networking system such as Facebook.

6.1 User information table

This table will be used to store the basic personal information of all the users, including their user name, contact information, registration time, IP address, etc.

6.2 Users’ Contacts table/ Association table

This table is used to store all the contacts/associations of each user, mainly their accounts.

6.3 Posts table

This table is used to store all the posts for different users. The columns should include post time, content, the number of likes, comments, the number of shares, and the accounts information of the shared user account.

7 References

Silberschatz, Abraham, Korth, Henry F. and Sudarshan, S., 2019. Database system concepts, 7 th edition. New York: McGraw-Hill.