Introduction to SQL - Week 9 Quiz

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Questions and Answers

What is the primary purpose of Business Intelligence (BI) systems?

To manage day-to-day database operations efficiently

To support management decisions with information for assessment and planning (correct)

To store large amounts of unstructured data

To create and analyze structured data models

Which SQL clause is used to specify conditions for filtering records?

WHERE (correct)

ORDER BY

FROM

GROUP BY

Which part of the SQL SELECT statement allows for returning unique values from a query?

GROUP BY

DISTINCT (correct)

ORDER BY

In the context of SQL, what does the asterisk (*) represent?

All available columns Signup and view all the answers

What is the role of the ORDER BY clause in an SQL query?

To specify the sorting order of the results Signup and view all the answers

What is one of the optional parts of the SELECT statement that is used with aggregate functions?

HAVING Signup and view all the answers

Which SQL command retrieves specific columns from a database table?

SELECT column_list FROM table_name; Signup and view all the answers

What is the correct syntax for an SQL query to select all records from a table named 'SKU_DATA'?

SELECT * FROM SKU_DATA; Signup and view all the answers

What does the SQL DISTINCT keyword achieve?

It eliminates duplicate records from the result. Signup and view all the answers

What is the function of SQL LIMIT?

To specify how many rows to return in a query. Signup and view all the answers

When using the WHERE clause, which of the following is NOT allowed?

Using slanted quotes for literal strings. Signup and view all the answers

Which operator would you use to check if a value is not within a specified range?

NOT BETWEEN Signup and view all the answers

In a WHERE clause, which operator could you use to identify records with a specific condition from a set of values?

IN Signup and view all the answers

How would you structure a query to find all records where the ExtendedPrice is between 100 and 200?

SELECT * FROM ORDER_ITEM WHERE ExtendedPrice BETWEEN 100 AND 200; Signup and view all the answers

What are aliases used for in SQL queries?

To rename columns or tables temporarily in the query. Signup and view all the answers

Which of the following is the correct way to apply a condition to exclude certain buyers from a result set?

WHERE Buyer NOT IN ('John Doe', 'Jane Smith'); Signup and view all the answers

Study Notes

Course Information

Course Title: Introduction to Database Systems
Course Code: CST 8215
College: Algonquin College
Week: 9
Topic: Introduction to Structured Query Language (SQL)

Business Intelligence (BI) Systems

BI systems are information systems used to support management decisions.
They produce information for assessment, analysis, planning, and control.
BI systems typically store their associated data in a data warehouse.

Data Warehouse Components

Operational Databases
Other Internal Data
External Data
ETL System (Data Extraction, Cleaning, Preparation Programs)
Data Warehouse Metadata
Data Warehouse Database
Data Warehouse DBMS
Business Intelligence Tools
BI Users

SQL SELECT/FROM/WHERE Framework

The fundamental framework for an SQL query is the SQL SELECT statement.
The SELECT statement is used to retrieve records from a database.
SQL statements end with a semi-colon (;).
The framework consists of these parts:
- SELECT (column names or *)
- FROM (table name)
- WHERE (conditions)
- GROUP BY (optional, with aggregate functions)
- HAVING (optional, with aggregate functions)
- ORDER BY (optional, to sort results)

SQL Syntax

SELECT [ALL | DISTINCT] {select list}
[INTO new table]
FROM {table source}
[WHERE search condition]
[GROUP BY group_expression]
[HAVING search condition]
[ORDER BY order clause]

Field List Options

*: Includes all columns
comma-separated list: Specifies specific columns

Specific Columns

Example: SELECT SKU, SKU Description, Department, Buyer FROM SKU_DATA;

Selecting All Columns (SQL Asterisk)

Example using *: SELECT * FROM SKU_DATA;

Specifying Column Order

Example: SELECT Department, Buyer FROM SKU_DATA;

Running an SQL Query in MySQL Workbench

The SQL editor is a tabbed window.
The query is entered into a tabbed window.
The execute button runs the query in the workbench.

Saving a MySQL Query

The saved scripts are in DBP-e15-Cape-Codd-Database.
The Save button saves the query to a file.

Reading Specified Rows

SQL DISTINCT keyword: Eliminates duplicate rows.
Example: SELECT DISTINCT Buyer, Department FROM SKU_DATA;

Controlling the Number of Rows

SQL LIMIT function: Controls the number of rows displayed.
Example: SELECT Buyer, Department FROM SKU_DATA LIMIT 5;

Conditional Statements (WHERE Clause)

Boolean expressions, several operators
Multiple clauses
Brackets

Using Single Quotes for Strings

Using single quotes is required when working with literal strings in the SQL WHERE clause.

SQL Comparison Operators

= (Equal to)
!= or <> (Not equal to)
(Greater than)
< (Less than)
= (Greater than or equal to)
<= (Less than or equal to)
IN (Equal to any value in a set)
NOT IN (Not equal to any value in a set)
BETWEEN (Within a range of values, inclusive)
NOT BETWEEN (Not within a range of values, inclusive)
LIKE (Matches a pattern)
NOT LIKE (Does not match a pattern)
IS NULL (Checks for NULL values)
IS NOT NULL (Checks for non-NULL values)

SQL WHERE Clause Using Sets

IN: Selects rows where a column value is present in a list.
NOT IN: Selects rows where a column value is not present in a list.
Examples provided

SQL WHERE Clause Using Math Symbols

Example (using > and < operators): SELECT * FROM ORDER_ITEM WHERE ExtendedPrice > 100 AND ExtendedPrice < 200;

SQL WHERE Clause Using BETWEEN Operator

Example: SELECT * FROM ORDER_ITEM WHERE ExtendedPrice BETWEEN 100 AND 200;

SQL WHERE Clause Using NOT BETWEEN Operator

Example: SELECT * FROM ORDER_ITEM WHERE ExtendedPrice NOT BETWEEN 100 AND 200;

SQL WHERE Clause Using Wildcard Symbols

The SQL LIKE operator can combine with wildcard symbols.
_ (underscore): Represents a single character
% (percent sign): Represents any sequence of characters
Examples of using these for pattern matching, including examples (using LIKE with 'Pete%') and examples (using LIKE with '%Tent%') and examples (using LIKE with '%2%') and example (using LIKE with '%2%')

SQL Where Clause Using NULL Operator

IS NULL: Selects rows where the specified column is NULL
IS NOT NULL: Selects rows where the specified column is NOt NULL

Using Dates in the WHERE Clause

Example: Using = with a date string '01-JAN-2020'

Using Numbers in the WHERE Clause

Example: SELECT * FROM SKU_DATA WHERE SKU > 200000;

Using Column Names in the WHERE Clause

Example: SELECT SKU_Description, Department FROM SKU_DATA WHERE Department = 'Climbing';

Aliases (Renaming)

AS keyword: Renames columns or tables for the duration of the query.
Example of using column alias: SELECT SUM(OrderTotal) AS OrderSum FROM RETAIL_ORDER;

Summary of Aliases

The AS keyword allows developers to rename columns or tables within an SQL query.
Column aliasing can improve query readability and data organization.
Using aliases is helpful when dealing with large tables, multi-table queries or complex calculations.
Example of using column aliasing: SELECT PetID AS ID, PetName AS Pet FROM Clinic;

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Description

Test your understanding of Structured Query Language (SQL) and its application in Business Intelligence systems. This quiz covers fundamental concepts like the SELECT statement, data warehouse components, and the role of SQL in data management. Prepare to demonstrate your knowledge of the SQL framework and its relevance to decision-making processes.