reading-notes

401 Class 1 Reading Notes

Summary: This class is about SQL

Relational databases store data in structured tables with rows and columns, ensuring efficient data management and retrieval. SQL is a standardized programming language used to interact with these databases, allowing users to create, manipulate, and retrieve data. The relational model and SQL work together to maintain data integrity and consistency while providing a powerful means for data storage and access.

Relational Database Components

  1. Tables (Relations): Store data in a structured format, with rows (tuples) representing individual records and columns (attributes) representing the properties of those records.
  2. Primary Key: A unique identifier for each row in a table, ensuring data integrity and enabling easy access to specific records.
  3. Foreign Key: A column or a set of columns in a table that refers to the primary key of another table, helping establish relationships between tables and maintain data consistency.
  4. Schema: Defines the structure of the database, including tables, columns, data types, and relationships between tables.
  5. SQL (Structured Query Language): A standardized programming language used to create, manipulate, and retrieve data from relational databases.
  6. Indexes: Database objects that improve query performance by providing a more efficient way to access data stored in tables.
  7. Constraints: Rules applied to columns or tables to enforce data integrity and maintain consistency.
  8. Views: Virtual tables derived from one or more existing tables, allowing users to access data without directly interacting with the underlying tables.
  9. Transactions: Sets of database operations executed as a single unit, ensuring data consistency and integrity, even in the case of errors or system failures.
  10. Normalization: A process of organizing data in a database to minimize redundancy and improve data integrity.

In summary, a relational database is a powerful data management system that organizes data into structured tables and utilizes various components to ensure data integrity, consistency, and efficient retrieval.

Bash Command Line Tutorial Summary Observations And Learnings

Linux is Case Sensitive

This is very important and a common source of problems for people new to Linux. Other systems such as Windows are case insensitive when it comes to referring to files. Linux is not like this. As such it is possible to have two or more files and directories with the same name but letters of different case.

Linux actually has a very simple and elegant mechanism for specifying that a file or directory is hidden. If the file or directory’s name begins with a . (full stop) then it is considered to be hidden.

Basic Navigation:

Command Description
pwd Print current working directory
cd Change directory
ls List contents of current directory
mkdir Create a new directory
rmdir Remove an empty directory
rm -r Remove a directory and its contents

More About Files:

Command Description
touch Create an empty file
cat Print the contents of a file to the terminal
less Display the contents of a file one page at a time
head Display the first few lines of a file
tail Display the last few lines of a file
mv Move or rename a file
cp Copy a file
rm Remove a file

Things I want to know more about

Things I want to know more about## Things I want to know more about