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Questions and Answers
What term is used to describe a complete set of data about one person, place, event, or idea?
What term is used to describe a complete set of data about one person, place, event, or idea?
In a relational database, how are the relationships between tables typically formed?
In a relational database, how are the relationships between tables typically formed?
Which of the following accurately describes a primary key?
Which of the following accurately describes a primary key?
What defines data in a database compared to information?
What defines data in a database compared to information?
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Which statement best describes a foreign key in a relational database?
Which statement best describes a foreign key in a relational database?
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What does the primary key in a database table do?
What does the primary key in a database table do?
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Which SQL command is used to retrieve specific columns from a table?
Which SQL command is used to retrieve specific columns from a table?
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In SQL, which operator is used to specify a filtering condition in the WHERE clause?
In SQL, which operator is used to specify a filtering condition in the WHERE clause?
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What can be inferred about a 'one-to-many' relationship between tables?
What can be inferred about a 'one-to-many' relationship between tables?
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What does the asterisk (*) represent in a SQL SELECT statement?
What does the asterisk (*) represent in a SQL SELECT statement?
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Study Notes
Database Basics
- A field is a basic data element, like a name or phone number.
- A record is a complete set of data about one thing (person, place, event, etc.).
- A table is a collection of records, where each record has the same fields in the same order.
- A database consists of one or more tables, plus supporting objects for data entry and retrieval.
Data vs. Information
- Data is the raw material of a database, in tables.
- Information is the result of transforming data, by selecting, sorting, or summarizing.
Relational Database
- Flat or non-relational data is in a single page or sheet.
- A relational database groups data into similar tables, with relationships between tables formed by common fields.
Keys
- Keys are attributes that identify other attributes and ensure unique rows.
- Primary key uniquely identifies a record.
- Foreign key is a primary key from another table, linking the tables together.
Table Example (Employee Data)
- A table example includes columns for Number, Name, Department, Salary, and Location.
- Each row represents an employee record, with associated data values.
- The Number column typically serves as the primary key, uniquely identifying each employee.
SQL Introduction
- SQL is relatively easy to learn, with a basic vocabulary of less than 100 words.
- SQL dialects have minor differences.
- Fundamental data types include character, numeric, and date data.
Basic SQL Structure
- A fundamental SQL structure involves SELECT, FROM, and WHERE clauses.
- SELECT specifies the columns to retrieve.
- FROM identifies the table to retrieve from.
- WHERE filters records based on conditions.
Operators in WHERE Clause
- Operators like =, >, <, >=, <=, BETWEEN, LIKE, and IN are used in the WHERE clause to filter data.
- Each operator has a specific function (equal to, greater than, etc).
Basic SQL Queries
- Retrieving specific data based on criteria.
- Ordering results using ORDER BY, ascending or descending.
- Examples include retrieving selected columns, filtering rows based on conditions, and sorting data in ascending or descending order based on a specified column.
Practice Questions (Table: Product)
- SQL queries to retrieve data based on the provided Product data table.
- Queries include retrieving product descriptions and prices, data related to a specific vendor code (232), and records that do not match specified criteria, sorted by price.
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Description
Explore the fundamentals of databases, including fields, records, and tables. Understand the difference between data and information, as well as the significance of keys in relational databases. This quiz covers essential concepts for anyone looking to grasp database structure and functionality.
