Northeastern University ITC 2811 Advanced Application Develo
Northeastern University Itc 2811 Advanced Application Development
For this assignment, you are required to write SQL queries based on specific instructions. Do not include screenshots or results—only list the queries.
1. Using the CREATE TABLE statement, create a table called City with the following columns: ID (INT, Primary Key, Not NULL), Name (VARCHAR(50), Not NULL), Region (VARCHAR(50), NULL), Population (INT, NULL), Year_Established (INT, NULL).
2. Write a query to select all unique Region values from the City table.
3. Write a query to select the Name values for all records where the Region is equal to "Northeast".
4. Write a query that returns all records where the Region is "Midwest" or the Population is less than 1,000,000.
5. Write a query that returns all records with a Population greater than 50,000 and whose Year_Established is NOT NULL.
Paper For Above instruction
SQL Queries for City Database and Analysis
Introduction
Structured Query Language (SQL) is an essential tool for managing and manipulating data within relational databases. This paper demonstrates the use of SQL commands through a series of queries designed to create, extract, and analyze data within a hypothetical City table. Each query adheres to standard SQL syntax and is constructed to fulfill specific informational requirements as outlined in the assignment instructions. By understanding these queries, one can develop foundational skills for database management, data analysis, and application development.
Creating the City Table
The first step in database development involves establishing the structure of the data repository. The City table is designed with the following columns: Id, Name, Region, Population, and Year_Established. The SQL command for creating this table is as follows:
CREATE TABLE City (
ID INT PRIMARY KEY NOT NULL,
Name VARCHAR(50) NOT NULL,
Region VARCHAR(50),
Population INT,
Year_Established INT
);
This statement ensures that each city has a unique identifier, a name, and optional attributes for regional classification, population size, and the year the city was established. The primary key constraint on ID maintains data integrity by preventing duplicate entries.
Retrieving Unique Regions
To analyze geographic distribution within the City table, it is necessary to identify distinct regions. The SQL query utilizing the DISTINCT keyword is employed for this purpose:
SELECT DISTINCT Region FROM City;This query returns a list of unique regions, which can be used for further geographic or demographic analysis. It filters duplicate entries, providing a clear overview of all regions represented in the data set.
Filtering Cities by Region
To extract the names of cities situated specifically in the Northeast region, the WHERE clause is used as follows:
SELECT Name FROM City WHERE Region = 'Northeast';This query retrieves all city names where the Region attribute matches 'Northeast', enabling targeted analysis of that geographic area.
Conditional Retrieval Based on Region and Population
To identify cities either located in the Midwest or having a small population, the OR logical operator combines conditions in the WHERE clause:
SELECT * FROM City WHERE Region = 'Midwest' OR Population This returns all records satisfying either of the two conditions, facilitating demographic and regional segmentation.
Filtering Based on Population and Known Year of Establishment
For studying established cities with significant populations, the following query is used:
SELECT * FROM City WHERE Population > 50000 AND Year_Established IS NOT NULL;This query ensures that only cities with a population exceeding 50,000 and having a recorded year of establishment are selected, useful for demographic and historical studies.
Conclusion
This set of SQL queries demonstrates standard practices for database creation, data retrieval, and conditional filtering. Mastery of such commands is fundamental for effective data management and analysis in application development and business intelligence. These queries can be integrated into larger database systems to support dynamic data interactions and reporting.
References
- Coronel, C., & Morris, S. (2015). Database Systems: Designing, Implementation, & Management. Cengage Learning.
- Database Concepts. Pearson.