# SQL Day 1

Given a table


Question 1 - Query the number of cities where population is larger than 100,000

answer-
Theory- COUNT is an aggregate function in SQL. Aggregate function is the function which takes multiple values as input and return a single value as the query output.

Select COUNT(ID) from CITY where POPULATION >100000;

Question 2-Query the total population of all cities in CITY where District is California.

answer-
Here, also the SUM is an Aggregate functions in SQL which returns the sum of values of a column

SELECT SUM(Population) FROM CITY WHERE District= 'California';

Question 3-Query the average population for all cities in CITY, rounded down to the nearest integer.

answer-
To round off a value, ROUND function is used. It is numeric function in SQL

answer-

SSELECT ROUND(AVG(Population)) from CITY;