csis1/16wk-week-12-14-databases.md

# Weeks 12–14: Databases (Microsoft Access)
**Hours:** 6 (3 lectures)

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## Learning Objectives
- Explain what a database is and why databases exist
- Distinguish between flat files (spreadsheets) and relational databases
- Create a database with tables, define fields and data types
- Enter, edit, and delete records
- Create and use forms for data entry
- Build queries to retrieve specific data
- Generate reports for presenting data
- Understand basic concepts: primary keys, relationships, data types

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## Lecture 12: What Is a Database? / Creating Tables

### Key Concepts

**Why Databases?**
Start with the problem spreadsheets can't solve well:

> 💡 **Scenario:** A college needs to track students, courses, and enrollments. In a spreadsheet, you'd repeat student info (name, address, phone) on every row where they're enrolled. One student in 5 classes = 5 copies of their address. What if they move? You update 5 rows. Miss one? Data is inconsistent.

A **database** solves this by storing each piece of information ONCE and linking related data together.

**Database Terminology**
- **Database:** An organized collection of structured data
- **Table:** A collection of related records (like a spreadsheet, but smarter)
- **Record (Row):** One complete entry (one student, one product, one order)
- **Field (Column):** One attribute of a record (name, phone number, grade)
- **Primary Key:** A unique identifier for each record (Student ID, Order #)
  - No two records can have the same primary key
  - Usually a number or auto-generated ID

> 💡 **Analogy:** A database is like a well-organized filing system. Each drawer (table) holds a type of document. Each folder (record) is one item. Each tab in the folder (field) is one piece of info. The label on the folder (primary key) is unique — no two folders have the same label.

**Flat File vs Relational Database**
| Feature | Spreadsheet (Flat File) | Database (Relational) |
|---------|----------------------|---------------------|
| Data stored | All in one table | Multiple linked tables |
| Redundancy | High (data repeated) | Low (data stored once) |
| Data integrity | Error-prone | Enforced by rules |
| Good for | Small, simple datasets | Large, complex, shared data |
| Example | Personal budget | College enrollment system |

**Data Types**
Every field has a data type that controls what can be entered:

| Data Type | What It Stores | Example |
|-----------|---------------|---------|
| Short Text | Text up to 255 characters | Name, City, State |
| Long Text | Longer text (memos, notes) | Description, Comments |
| Number | Numeric values | Age, Quantity |
| Currency | Money values | Price, Salary |
| Date/Time | Dates and/or times | BirthDate, OrderDate |
| Yes/No | Boolean (true/false) | Enrolled?, Active? |
| AutoNumber | Auto-incrementing unique ID | StudentID, OrderID |

**Creating a Table in Access**
1. Open Access → Blank Database → Name it
2. Table Design View: Define field names, data types, descriptions
3. Set the Primary Key (usually an AutoNumber field)
4. Save the table with a descriptive name (tblStudents, tblCourses)
5. Switch to Datasheet View to enter data

> 💡 **Naming convention tip:** Prefix table names with "tbl", queries with "qry", forms with "frm", reports with "rpt". Keeps the Navigation Pane organized.

### Diagram Ideas
1. **Spreadsheet vs Database** — Left: spreadsheet with repeated student data across rows. Right: two linked tables (Students, Enrollments) with no repetition.
2. **Database Anatomy** — Visual showing Database → Tables → Records → Fields → Values.
3. **Primary Key Concept** — Table with highlighted primary key column; show that each value is unique.
4. **Data Types Reference Card** — Visual grid of each type with icon and example.

### Slide Concepts
| Slide | Content |
|-------|---------|
| 1 | Title: "Databases: Organized Information" |
| 2 | The Problem with Spreadsheets — duplicate data scenario |
| 3 | What Is a Database? — key terminology |
| 4 | Flat File vs Relational — comparison table |
| 5 | Tables, Records, Fields, Primary Keys — visual breakdown |
| 6 | Data Types — reference chart |
| 7 | Demo: Create a table in Design View |
| 8 | Naming Conventions — tbl, qry, frm, rpt |

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## Lecture 13: Forms & Queries

### Key Concepts

**Relationships (brief intro)**
- Tables can be **related** through shared fields
- Example: tblStudents has StudentID. tblEnrollments has StudentID + CourseID. The StudentID field links them.
- **One-to-Many:** One student → many enrollments. One course → many enrollments.
- Relationships enforce **referential integrity** — can't enroll a student that doesn't exist.

> 💡 **Visual:** Draw two tables on the board with a line connecting the shared field. This is the foundation of relational thinking.

**Forms**
- A user-friendly interface for entering and viewing data (instead of raw table view)
- **Create → Form:** Auto-generates a form from a table
- **Form Design View:** Customize layout, add labels, controls, colors
- Forms can include:
  - Text boxes (bound to fields)
  - Drop-down lists (combo boxes) — limit input to valid choices
  - Buttons (for navigation, saving)
- **Why forms?** Reduce data entry errors, look professional, can hide complexity.

> 💡 **Teaching idea:** Show data entry in Datasheet View vs a Form. The form is immediately more intuitive and less error-prone. "This is what real database applications look like."

**Queries**
Queries ask questions of your data. They're the power of databases.

- **Select Query:** Retrieve specific records and fields
  - "Show me all students from Gilroy"
  - "Show me all orders over $100"
- **Query Design View:** Drag fields, set criteria, choose sort order
- **Criteria Operators:**
  - `= "Gilroy"` — exact match
  - `> 100` — greater than
  - `Like "S*"` — starts with S (wildcard)
  - `Between #1/1/2024# And #12/31/2024#` — date range
  - `Is Not Null` — field is not empty
- **Calculated Fields:** Create new fields in queries
  - Example: `TotalPrice: [Quantity]*[UnitPrice]`
- **Sorting:** A→Z, Z→A, smallest→largest within the query
- **Multiple criteria:** AND (same row in QBE grid) vs OR (different rows)

> 💡 **Demo:** Using the student/enrollment tables, query: "Show me all students enrolled in CSIS 1 who live in Gilroy." Build it step by step in Design View.

### Diagram Ideas
1. **One-to-Many Relationship** — tblStudents (one) linked to tblEnrollments (many) with a line and 1→∞ symbols.
2. **Form vs Datasheet** — Side-by-side: messy datasheet view vs clean, labeled form.
3. **Query Design View Explained** — Annotated screenshot: field row, table row, sort row, show checkbox, criteria row.
4. **AND vs OR in Criteria** — Visual: two conditions on same row = both must be true (AND). Two conditions on different rows = either can be true (OR).

### Slide Concepts
| Slide | Content |
|-------|---------|
| 1 | Title: "Asking Questions of Your Data" |
| 2 | Relationships — linking tables, one-to-many |
| 3 | Forms — why they exist, auto-generate demo |
| 4 | Form vs Datasheet — side-by-side |
| 5 | What Is a Query? — asking questions |
| 6 | Query Criteria — operators and examples |
| 7 | Wildcards and Ranges — Like, Between |
| 8 | Calculated Fields — building expressions |
| 9 | Demo: Multi-criteria query |

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## Lecture 14: Reports & Database Review

### Key Concepts

**Reports**
- Formatted, printable output from tables or queries
- **Create → Report:** Auto-generates from selected table/query
- **Report Design View:** Customize layout, grouping, totals
- Report sections: Report Header/Footer, Page Header/Footer, Detail (repeated per record), Group Header/Footer
- **Grouping:** Organize records by a field (group by city, by course, by date)
- **Summary calculations:** Sum, Count, Average in group footers or report footer

> 💡 **Example:** Generate a report of all students grouped by major, with a count of students per major and a grand total at the bottom.

**Putting It All Together**
The database workflow:
1. **Design tables** with proper fields, data types, and primary keys
2. **Define relationships** between tables
3. **Enter data** via forms (user-friendly)
4. **Ask questions** with queries (retrieve/analyze)
5. **Present results** with reports (formatted output)

> 💡 **Teaching idea:** Walk through a complete mini-project: a small business inventory database. Create tables (Products, Categories, Orders), enter data via forms, query for low-stock items, generate an inventory report.

**Data Integrity Best Practices**
- Always use a primary key
- Use appropriate data types (don't store phone numbers as Number — use Text to preserve leading zeros and formatting)
- Use input masks for formatted fields (phone: (###) ###-####)
- Set required fields where data must be entered
- Use validation rules (e.g., grade must be between 0 and 100)
- Use lookup fields / combo boxes to limit choices to valid entries

### Diagram Ideas
1. **Database Workflow** — Flow diagram: Design Tables → Define Relationships → Enter Data (Forms) → Query Data → Generate Reports.
2. **Report Anatomy** — Labeled report showing header, page header, group header, detail rows, group footer with subtotal, report footer with grand total.
3. **Complete Database Example** — Entity diagram showing 3 tables with relationships (e.g., Customers → Orders → Products).

### Slide Concepts
| Slide | Content |
|-------|---------|
| 1 | Title: "Reports & Big Picture" |
| 2 | What Are Reports? — formatted printable output |
| 3 | Creating a Report — auto-generate and customize |
| 4 | Grouping & Totals — organizing report data |
| 5 | The Database Workflow — design → forms → queries → reports |
| 6 | Data Integrity — rules and best practices |
| 7 | Phone Numbers as Text — a common gotcha |
| 8 | Review: Databases vs Spreadsheets — when to use each |

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## Vocabulary

| Term | Definition |
|------|-----------|
| **Database** | An organized collection of structured data, typically stored and accessed electronically |
| **Table** | A structure that stores data in rows (records) and columns (fields) |
| **Record** | A single row in a table; one complete entry |
| **Field** | A single column in a table; one attribute of a record |
| **Primary Key** | A unique identifier for each record in a table |
| **Data Type** | The kind of data a field can hold (Text, Number, Date, etc.) |
| **Relational Database** | A database where tables are connected through shared fields (relationships) |
| **Relationship** | A connection between two tables based on a common field |
| **One-to-Many** | A relationship where one record in Table A relates to multiple records in Table B |
| **Referential Integrity** | A rule ensuring relationships between tables remain consistent |
| **Form** | A user-friendly interface for entering and viewing data in a table |
| **Query** | A request for specific data from a database; retrieves records matching criteria |
| **Criteria** | Conditions that filter which records a query returns |
| **Wildcard** | A character (like `*`) used in criteria to match any sequence of characters |
| **Calculated Field** | A field in a query that computes a value from other fields |
| **Report** | A formatted, printable presentation of data from tables or queries |
| **Grouping** | Organizing report records by the values in a specified field |
| **Flat File** | A database consisting of a single table (like a spreadsheet) |
| **Input Mask** | A pattern that controls how data is entered in a field (e.g., phone number format) |
| **Validation Rule** | A condition that data must meet to be accepted into a field |
| **AutoNumber** | A data type that automatically generates a unique sequential number |
| **Combo Box** | A form control that provides a dropdown list of valid choices |

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## Activities & Assignments

### In-Class
1. **Table Design Exercise:** Given a scenario (library, pizza shop, or student club), design the tables: identify fields, choose data types, select primary keys, and identify relationships.
2. **Query Challenge:** Provide a populated database. Students answer 10 questions by building queries (e.g., "Which products cost more than $50?" "How many customers are from California?").
3. **Form & Report Walkthrough:** Build a form and report together from the same data.

### Homework / Projects
1. **Mini-Database Project:** Design and build a small database for a chosen scenario (personal media collection, recipe book, fitness tracker, small business). Requirements:
   - At least 2 related tables
   - 10+ records per table
   - 1 form for data entry
   - 2 queries (one with criteria, one with a calculated field)
   - 1 grouped report with totals
   - Brief write-up explaining the design decisions

2. **Real-World Database Hunt (1 page):** Identify 3 databases you interact with in daily life (banking, social media, school enrollment, online shopping). For each: what tables might it have? What would the primary keys be? How are they related?

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## Discussion Questions
1. Your boss asks you to track inventory in a spreadsheet. At what point should you move to a database?
2. Why do we need primary keys? What happens if two records have identical information in every field?
3. A database stores your health records, purchase history, and location data. What are the benefits and risks?
4. Why is it a mistake to store a phone number as a Number data type?