Module 7 — Databases

Module 7 · week of 10/12/2026 · Tech+: Data and Database Fundamentals — tables, records, fields, primary keys, relational databases, queries, data types, and why data is stored in a database instead of a spreadsheet. · Download .docx

Objectives

Perform basic proficiency in data analysis using software.

Key terms

Database: An organized collection of related data that many users and programs can share.
Table: A set of records about one kind of thing, arranged in rows and columns.
Record: One row of a table — all the fields for one item, such as one student.
Field: One column of a table — one kind of information, such as Last Name.
Data type: The kind of value a field holds: text, number, date, currency, yes/no.
Primary key: The field that uniquely identifies each record, such as Student ID.
Foreign key: A field in one table that refers to the primary key of another table, creating a relationship.
Relational database: A database that stores data in several related tables connected by keys.
Normalization: Organizing tables so each fact is stored once, to avoid repeated and conflicting data.
DBMS: Database management system — software that creates, manages, and secures databases (Access, MySQL, SQL Server).
Query: A request for specific data from a database.
SQL: Structured Query Language — the standard language for querying and changing relational databases.
SELECT: The SQL statement that retrieves data from a table.
WHERE: The SQL clause that filters which records are returned.
Form: A screen for entering or editing records in a database.
Report: Formatted output from a database, designed to be read or printed.
Validation rule: A check that stops incorrect data from being entered, such as a grade outside 9–12.
Big data: Data sets so large, fast, or varied that traditional tools struggle to process them.
Data warehouse: A large store that collects data from many systems so it can be analyzed together.
Data mining: Searching large data sets for patterns and relationships.

The concept

A database is an organized collection of related data that many people and programs can use at the same time. A spreadsheet is fine for one person's list; a database is built for many users, large volumes, and questions asked over and over.

A table stores one kind of thing (students, courses, orders). Each row is a record — one student. Each column is a field — Last Name, Grade, Phone Number. Every field has a data type: text, number, date, currency, yes/no.

The primary key is the field that uniquely identifies each record — Student ID, not Last Name, because two students can share a name. No two records may have the same primary key, and it may not be blank.

A relational database stores data in several tables and connects them with keys. A foreign key in one table (Course ID in the Enrollment table) points to the primary key of another (Course ID in the Courses table). That link is the relationship.

Why split data into tables? To avoid repeating it. If every enrollment row also stored the student's full address, a change of address would have to be made in dozens of rows. Store the address once, in the Students table, and link by Student ID. This is normalization.

A database management system (DBMS) is the software that creates, stores, secures, and answers questions about the data: Microsoft Access, MySQL, Microsoft SQL Server, Oracle, PostgreSQL.

A query is a question you ask the database. SQL (Structured Query Language) is the standard language for asking it. SELECT * FROM students; returns every column of every student. SELECT last_name, grade FROM students WHERE grade = 9; returns only the 9th graders' names and grades.

SQL verbs to know: SELECT reads data, INSERT adds a record, UPDATE changes a record, DELETE removes one. WHERE filters rows; ORDER BY sorts them.

Forms are how people enter data into a database; reports are formatted output for people to read; queries sit in between. Access uses all three on top of its tables.

Data quality matters: a database is only as good as what goes in. Validation rules (a grade must be 9–12, a date must be a real date) stop bad data at the door.

Big data means data sets so large, fast, or varied that traditional tools struggle: web clicks, sensors, video, social posts. Data warehouses collect data from many systems for analysis; business intelligence and data mining find patterns in it.

Databases carry responsibility: personal data (grades, addresses, health) must be protected, and only people with a need should be able to read it. Prof. Roberts' Canvas gradebook is a database with exactly those rules.

Module 7 items: Database Assignment (50) and Module 7 Quiz (20) — 70 points, the week of Oct 12. Module 8 (The People in Information Systems) follows the week of Oct 19.

Worked examples

Example 1: Design a table for the P-TECH IT roster: pick five fields, give each a data type, and choose the primary key. Why not use Last Name as the key? — Fields: Student ID (number, primary key), Last Name (text), First Name (text), Grade (number, 9–12), Class Year (number). Last Name cannot be the key because two students can share it and a key must be unique and never blank.

Example 2: Write the SQL that lists the last names of every 9th grader in a students table, then the SQL that returns everything in the table. — SELECT last_name FROM students WHERE grade = 9; and SELECT * FROM students; — SELECT chooses the columns, FROM names the table, WHERE filters the rows, and * means every column.

Example 3: A school keeps one giant spreadsheet where every quiz score row repeats the student's name, address, and phone. A student moves. What goes wrong, and how would a relational database fix it? — The address must be changed in every row that student appears in; miss one and the data conflicts. In a relational database the address is stored once in a Students table, scores live in a Scores table with the Student ID as a foreign key, and one update fixes every score row — that is normalization.

Common mistakes

"A spreadsheet and a database are the same thing." A spreadsheet is one person’s grid; a database is built for many users, large volumes, and repeated queries, with keys and validation rules.
"The primary key can be the student’s name." A key must be unique and never blank — two students can share a name, so use Student ID.
"SELECT deletes or changes data." SELECT only reads. INSERT adds, UPDATE changes, DELETE removes.

Self-check

Try each one before you look. A miss here costs nothing and tells you exactly what to reread.

1. In a database, a single row that describes one customer is called a:

2. In a database table, a column such as Last Name or Phone Number is called a:

3. A field that uniquely identifies each record, such as Student ID, is called the:

4. A database that stores data in related tables connected by keys is called a:

5. Which SQL statement retrieves data from a table?

Canvas is the official record. This companion enhances the PGCC curriculum; it does not replace it. Last name and class year only. Students with a 504 plan or IEP: your accommodations apply.

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