Rename year directories to allow natural ordering

2023-12-20 03:57:27 +00:00
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--- a/year2/semester1/logseq-stuff/pages/Database
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+- #[[CT230 - Database Systems I]]
+- No previous topic
+- **Next Topic:** [[The Relational Model]]
+- **Relevant Slides:** ![Lecture01.pdf](../assets/Lecture01_1662845512365_0.pdf)
+-
+- What is a **database**? #card
+  card-last-interval:: 64.01
+  card-repeats:: 5
+  card-ease-factor:: 2.52
+  card-next-schedule:: 2023-01-24T13:09:54.692Z
+  card-last-reviewed:: 2022-11-21T13:09:54.692Z
+  card-last-score:: 5
+	- A **database** is ^^a collection of related data.^^
+-
+- What is the **Database Approach**? #card
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+  card-next-schedule:: 2022-11-22T10:36:04.634Z
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+  card-last-score:: 3
+	- A **single repository** of data (which may be distributed) is maintained that is **defined once** and then accessed by various users via a **DBMS**.
+- ## Database Management Systems
+	- What is a **DBMS**? #card
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+	  card-repeats:: 4
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+	  card-next-schedule:: 2022-12-03T16:40:07.862Z
+	  card-last-reviewed:: 2022-11-14T16:40:07.862Z
+	  card-last-score:: 5
+		- The **DataBase Management System (DBMS)** is a collection of programs that facilitates the process of ^^defining, constructing, & manipulating^^ databases for various applications.
+	- ### DBMS Capabilities #card
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+	  card-repeats:: 4
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+	  card-next-schedule:: 2022-12-03T16:44:40.304Z
+	  card-last-reviewed:: 2022-11-14T16:44:40.304Z
+	  card-last-score:: 3
+		- 1. **Define** database (DDL)
+		  2. **Manipulate** database (SQL)
+		  3. **Control** redundancy
+		  4. **Restrict** unauthorised access
+		  5. **Enforce** integrity constraints
+		  6. Provide multiple user interfaces / **views**
+		  7. Provide **concurrent access**
+		  8. Provide mechanism for **recovery**
+		  9. Provide **back-up**
+		  10. Allows representation of complex relationships between data (For efficiency & optimisation reasons)
+		-
+	- ### Disadvantages of DBMS approach #card
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+	  card-repeats:: 4
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+	  card-next-schedule:: 2022-12-08T02:39:24.701Z
+	  card-last-reviewed:: 2022-11-14T16:39:24.701Z
+	  card-last-score:: 3
+		- Strict schema & multiple tables / relations
+		- Complexity
+		- Size
+		- Cost of DBMS
+		- Additional hardware costs
+		- Cost of conversion
+		- Performance
+		- Higher impact of failure
+	- ### DBMS Users #card
+	  card-last-interval:: 7.76
+	  card-repeats:: 3
+	  card-ease-factor:: 1.94
+	  card-next-schedule:: 2022-11-22T10:36:32.717Z
+	  card-last-reviewed:: 2022-11-14T16:36:32.718Z
+	  card-last-score:: 3
+		- **Administrators (DBA)** - accounts, passwords, privileges. Requiring constant vigilance
+		- **System Analysts** - "What's required to solve a problem? What does the business need?"
+		- **Designers** - ER diagrams, mapping ER diagrams to tables
+		- **Application Programmers** - creating tables, adding data, creating queries
+		- **End users**
+-
+- What is **Database Abstraction**? #card
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+  card-next-schedule:: 2022-12-18T19:23:19.167Z
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+  card-last-score:: 3
+	- **Database Abstraction** refers to the hiding of the details of data storage that are not needed by most database users.
+	- The aim is to separate user's views of the database from the way that it is "physically" represented.
+	- 3 ways in which data can be described:
+		- **External:** user's view
+		- **Conceptual:** logical structure as seen by DBA
+		- **Internal:** DBMS and OS view of data
+- What is the database **schema**? #card
+  card-last-interval:: 4
+  card-repeats:: 2
+  card-ease-factor:: 2.52
+  card-next-schedule:: 2022-11-18T20:24:46.045Z
+  card-last-reviewed:: 2022-11-14T20:24:46.046Z
+  card-last-score:: 5
+	- The database **schema** is the ^^logical structure of the database.^^
+- What is the database **instance**? #card
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+  card-last-reviewed:: 2022-11-14T20:00:02.004Z
+  card-last-score:: 5
+	- The database **instance** is ^^the actual content of the database at some point in time.^^
+-
+-