###### tags: `database` `note` `thu`
# DB-目錄
## Two taboos of database:
### 1. Null value
#### There are 2 possible cases for this situation:
- not applicable
- unknown
### 2. Redundancy
#### This may cause problems when you need to update the data.
## **目錄**
### [Introduction](/V8N0VLYcQESEkfW_rP3bZw)
### [ER Model](/Nyrko5UcQBukCUFDTrCm1Q) | [EER Model (施工中)](/ntwp0SGHRQulR3R8ttxEzw)
### ER/EER Diagram至Schema的轉換
- [課本 (ER Diagram)](/rGnIb6g0RVyYuq9urMynEA) | [課本 (EER Diagram) (施工中)](/nEdLM7v8TGSez2nuv9YjJw)
- [老師筆記 ver.](/GK34a_FiRhSZHvJPx3m4ag)
### [The Relational Algebra and Relational Calculus](/GfqdB-I5Rwm-ZjLNQmh4bQ)
### [Basic SQL](/74aWZFxRQoWImVHSFAT0DQ)
### File and Indexing Structures
#### 1. [File structure](/Up6trtGZR2ukoCByy3XGcg)
#### 2. [Indexing Structures](/HrDt22JbSAuhJfKxdjLpAg)
#### 3. [B-Tree](/wcCtFd90Q12UWzPnpC06SQ)
## **作業**
### HW1 Deadline: 12/5 (一)
使用Complete set裡的元素 $\{\sigma , \pi, \times, -, \cup\}$來組合成下列三種運算:
1. join
2. Outer join
3. Outer union
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