Database Relationships and Integrity

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Questions and Answers

What is the highest closing price recorded on January 4th, 1990?

24.56

24.35

24.84 (correct)

25.06

Which of the following SQL commands correctly retrieves all rows from the IBM table?

RETRIEVE ALL FROM IBM;

SELECT * FROM IBM; (correct)

GET * FROM IBM;

FETCH * FROM IBM;

In the relational database structure of Options.sqlite, which table contains information about stock trades?

Options

Stock

StockTrades (correct)

OptionContracts

What is the primary key that connects the Stock and StockTrades tables in the Options.sqlite database?

StockSymbol Signup and view all the answers

What type of relationships exist between the tables of the Options.sqlite database?

One-to-many Signup and view all the answers

Which date has the lowest recorded open price from the provided data?

2-Jan-90 Signup and view all the answers

What is the purpose of the foreign key in the StockTrades table?

To link trades to specific stocks Signup and view all the answers

Which of the following values represents the volume of trades on January 8th, 1990?

1159800 Signup and view all the answers

What type of file extension is used for SQLite databases?

.sqlite Signup and view all the answers

What is the purpose of the validation table in the Finance.sqlite database?

To contain ticker symbols. Signup and view all the answers

Which SQL statement is used to create the Prices table in the SQLite database?

CREATE TABLE Prices(Symbol TEXT, Date DATE, Price FLOAT, Volume INT32) Signup and view all the answers

When inserting data into the Prices table, which data type is used for the Price field?

FLOAT Signup and view all the answers

What does the fetchall method return after querying the Prices table?

A list of tuples Signup and view all the answers

Which of the following stocks is NOT included among the tables in the Finance.sqlite database?

AAPL Signup and view all the answers

What does the SQLite database engine claim about its deployment?

It is the most widely deployed database in the world. Signup and view all the answers

What is a characteristic feature of SQLite as mentioned in the content?

Self-contained and serverless Signup and view all the answers

What defines a relationship as many-to-many in a database?

A single record in each table relates to multiple records in the other. Signup and view all the answers

Which statement correctly describes foreign keys in a database schema?

Foreign keys can refer to primary keys in another table. Signup and view all the answers

What is the main purpose of normalization in database design?

To minimize redundancy and update anomalies in the database. Signup and view all the answers

Which normal form ensures that a table has no partial dependencies?

Second normal form. Signup and view all the answers

What does a schema in database terms primarily define?

The relationships and structure of the database including tables and fields. Signup and view all the answers

What is required to establish a one-to-many relationship in a database?

A primary key in the first table that references multiple foreign keys in the second table. Signup and view all the answers

What is typically done to ensure integrity constraints in a database schema?

Normalization processes are used to verify compatibility of structures. Signup and view all the answers

How is a linking table used in a many-to-many relationship?

By combining primary keys from both related tables into one table. Signup and view all the answers

What type of relationship exists between the Stock and OptionContracts tables?

One-to-many relationship Signup and view all the answers

Which SQL statement is primarily used to retrieve data from a database?

SELECT Signup and view all the answers

What does DML stand for in SQL?

Data Manipulation Language Signup and view all the answers

Which of the following correctly describes a DDL operation?

Creating a new database table Signup and view all the answers

Which SQL commands are included under Data Control Language (DCL)?

GRANT and REVOKE Signup and view all the answers

What is a common application of SQL in quantitative trading or risk management systems?

Data retrieval Signup and view all the answers

What distinguishes Transact-SQL from standard SQL?

It is a vendor-specific extension Signup and view all the answers

Which of the following best describes what a SELECT statement does?

It queries the database for specific data. Signup and view all the answers

Which clause is essential in a SELECT statement?

FROM clause Signup and view all the answers

What must separate multiple columns in the SELECT statement?

Comma Signup and view all the answers

How is SQL case sensitivity characterized?

SQL is case insensitive. Signup and view all the answers

What symbol is used to select all columns from a table?

<ul> <li></li> </ul> Signup and view all the answers

Which operator is used to filter rows by checking for equality in the WHERE clause?

= Signup and view all the answers

What does the BETWEEN operator do in a SQL query?

Selects values within a specified range. Signup and view all the answers

What is the correct way to terminate an SQL statement in most databases?

With a semicolon. Signup and view all the answers

In a SELECT statement, which clause helps to filter results based on specific conditions?

WHERE clause Signup and view all the answers

Study Notes

Relationships between tables

Relationships occur when a primary key in one table matches a foreign key in another table.
Foreign keys can have null or duplicate values, and they reference primary keys in other tables.
One-to-one: A single record in the first table corresponds to a single record in the second table, and vice versa.
One-to-many: A single record in the first table can be related to multiple records in the second table, but a single record in the second table can only correspond to one in the first.
Many-to-many: A single record in the first table can be related to multiple records in the second table, and vice versa. A linking table is created to handle this relationship by copying the primary keys from each table into the new table.

Database Schema and Integrity

A schema defines the database structure, including tables, fields, relationships, etc.
Integrity constraints ensure compatibility between various components of the schema.
Formulas within a schema can represent integrity constraints for specific applications.

Normalization

A process of optimizing database schemas to minimize redundancies and issues with data insertion, deletion, and updating.
A complex schema is often decomposed into smaller schemas for optimization.
Normal forms (at least five exist) are sets of rules that assess table structure for soundness and error-free designs.

SQLite

SQLite is an open-source, self-contained, serverless, zero-configuration, SQL database engine.
It is widely deployed and stores data directly in disk files with an .sqlite extension.
Python can create and access SQLite databases.

Finance.sqlite

This database holds daily historical price data for 13 stocks and the S&P 500.
Data tables are named after their corresponding tickers (e.g., AXP, GE, IBM, etc.).
A Tickers validation table contains a single column (Symbols) listing the unique ticker symbols.

Options.sqlite

This database utilizes a relational structure to store information about stocks, options, and related trades.
It consists of four tables: Stocks, OptionContracts, StockTrades, and OptionTrades.
Relationships are established through primary and foreign keys (e.g., StockSymbol in the Stock table and the StockTrades table).
The relationships in this database are all one-to-many.

Structured Query Language (SQL)

SQL is a standardized language for database communication and interaction, designed to be cross-platform.
Database vendors often extend ANSI/ISO SQL with their own versions (e.g., Transact-SQL, PL/SQL).
Python can embed SQL statements, enabling various database operations from data retrieval to structural changes.

SQL Statement Categories

Data Query Language (DQL): Used for data retrieval.
Data Manipulation Language (DML): Used for writing, changing, or deleting data.
Data Definition Language (DDL): Used to modify the database structure.
Data Control Language (DCL): Involves commands like GRANT and REVOKE, which control access privileges.

DML (Data Manipulation Language)

SELECT: The primary command used to retrieve data from a database.
SELECT Statement Clauses:
- FROM: Required clause specifying the table to query.
- WHERE: Used to filter results based on specific conditions.
- ORDER BY: Used to sort the returned results.
- GROUP BY: Used to group rows with the same values based on specified columns.
- HAVING: Used to filter grouped results.
Comparison Operators:
- <: Less than.
- >: Greater than.
- >=: Greater than or equal to.
- =: Equals.
- <>: Not equal to.
- BETWEEN: To check if the value lies within a specified range.

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Description

This quiz explores the concepts of table relationships within a database, including one-to-one, one-to-many, and many-to-many relationships. It also covers the importance of database schema and integrity constraints that maintain the consistency and validity of data. Test your knowledge and understanding of these fundamental database principles.