1. Group by function
The group by function will categroy the table according to different requirement:
Select Employed, Major_category, SUM(Employed) FROM recent_grads GROUP BY Major_category; #Here, in the table, the program first group by Employed and Major_category. Then they use aggregate function to get the result.
2. If we would like to change name of each column in the query result, we can use AS function:
Select sum(Men) as total_men, sum(Women) as total_women from recent_grads;
3. When we use AS, we choose HAVING instead of WHERE:
Select Major_category, Avg(low_wage_jobs)/ Avg(Total) as share_low_wage from recent_grads group by Major_category having share_low_wage > 0.1;
4. We use round function to round values when query them:
SELECT Major_category, ROUND(ShareWomen, 2) AS rounded_share_women
FROM recent_grads; # Round the ShareWomen column to 2 decimal places