Hackerrank - SQL - Revising the Select Query I
Mr Punk da Silva

Mr Punk da Silva @mrpunkdasilva

About: I'm a Brazilian Software Engineer passionate about creating elegant solutions for complex problems. I specialize in full-stack development with a focus on clean code, solid architecture, and exception

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Jul 19, 2023

Hackerrank - SQL - Revising the Select Query I

Publish Date: Jul 15
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Problem Description

Query all columns for all American cities in the CITY table with populations larger than 100000. The CountryCode for America is USA.

Input Format

The CITY table is described as follows:

Field Type
ID NUMBER
NAME VARCHAR2(17)
COUNTRYCODE VARCHAR2(3)
DISTRICT VARCHAR2(20)
POPULATION NUMBER

Solution Approach

  1. Use a SELECT statement to query all columns (*) from the CITY table
  2. Apply a WHERE clause with two conditions:
    • POPULATION >= 100000 (cities with populations larger than 100000)
    • COUNTRYCODE = "USA" (cities in America)

Step-by-Step Explanation

  1. Start with the basic SELECT statement to retrieve all columns:
   SELECT *
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  1. Specify the table to query from:
   FROM CITY
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  1. Add the WHERE clause with the required conditions:
   WHERE POPULATION >= 100000 AND COUNTRYCODE = "USA"
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  1. The final query:
   SELECT
   *
   FROM CITY
   WHERE POPULATION >= 100000 AND COUNTRYCODE = "USA";
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Expected Output

The query will return all columns (ID, NAME, COUNTRYCODE, DISTRICT, POPULATION) for cities in the USA with populations greater than 100000.

Repo: https://github.com/mrpunkdasilva/hackerrank/tree/main/sql/basic/revising-the-select-query-1

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