learn-co-curriculum/sql-queries-with-aggregate-functions-lab

Aggregate Functions Lab

Introduction

In this lab we will query data from a table populated with Babe Ruth's career hitting statistics. We will use aggregate functions to pull interesting information from the table that basic queries cannot track. We will discover many interesting facts about Babe Ruth, like his total career homeruns and his most homeruns in one season.

Objectives

1. Write queries with aggregate functions like COUNT, MAX, MIN, and SUM
2. Create an alias for the return value of an aggregate function
3. Use GROUP BY to sort the data sets returned by aggregate functions
4. Compare aggregates using the HAVING clause

Babe Ruth -- Career Hitting Statistics

We will query from the babe_ruth_stats table featured below. Write your queries as strings inside the functions already defined in select.py.

year	team	league	doubles	triples	hits	HR	games	runs	RBI	at_bats	BB	SB	SO	AVG
1914	"BOS"	"AL"	1	0	2	0	5	1	2	10	0	0	4	0.2
1915	"BOS"	"AL"	10	1	29	4	42	16	21	92	9	0	23	0.315
1916	"BOS"	"AL"	5	3	37	3	67	18	15	136	10	0	23	0.272
1917	"BOS"	"AL"	6	3	40	2	52	14	12	123	12	0	18	0.325
1918	"BOS"	"AL"	26	11	95	11	95	50	66	317	58	6	58	0.3
1919	"BOS"	"AL"	34	12	139	29	130	103	114	432	101	7	58	0.322
1920	"NY"	"AL"	36	9	172	54	142	158	137	458	150	14	80	0.376
1921	"NY"	"AL"	44	16	204	59	152	177	171	540	145	17	81	0.378
1922	"NY"	"AL"	24	8	128	35	110	94	99	406	84	2	80	0.315
1923	"NY"	"AL"	45	13	205	41	152	151	131	522	170	17	93	0.393
1924	"NY"	"AL"	39	7	200	46	153	143	121	529	142	9	81	0.378
1925	"NY"	"AL"	12	2	104	25	98	61	66	359	59	2	68	0.29
1926	"NY"	"AL"	30	5	184	47	152	139	146	495	144	11	76	0.372
1927	"NY"	"AL"	29	8	192	60	151	158	164	540	137	7	89	0.356
1928	"NY"	"AL"	29	8	173	54	154	163	142	536	137	4	87	0.323
1929	"NY"	"AL"	26	6	172	46	135	121	154	499	72	5	60	0.345
1930	"NY"	"AL"	28	9	186	49	145	150	153	518	136	10	61	0.359
1931	"NY"	"AL"	31	3	199	46	145	149	163	534	128	5	51	0.373
1932	"NY"	"AL"	13	5	156	41	133	120	137	457	130	2	62	0.341
1933	"NY"	"AL"	21	3	138	34	137	97	103	459	114	4	90	0.301
1934	"NY"	"AL"	17	4	105	22	125	78	84	365	104	1	63	0.288
1935	"BOS"	"NL"	0	0	13	6	28	13	12	72	20	0	24	0.181

Queries

total_seasons

Counts the total number of years that Babe Ruth played professional baseball

total_seasons_with_ny

Counts the total number of years played with the NY Yankees

most_hr

Selects the most HR that Babe Ruth hit in one season

least_hr

Select the least number of HR hit in one season

total_hr

Returns the total number of HR hit by Babe Ruth during his career

average_hr_per_year

Returns the average number of HR hit in a given year

year_and_games_with_least_hr

In the previous query, we learned that Babe Ruth hit 0 HR one year. That statistic might not be indicative of a typical Babe Ruth season if he played in only a handful of games that year. Let's figure out how many games he played that season. Select the year and games from the season in which Ruth hit 0 HR.

select_yr_and_min_hr_with_at_least_100_games

We determined that Babe Ruth hit 0 homeruns in his first year, when he played only five games. Let's avoid the outliers by looking at years in which Ruth played in at least 100 games. Select the year with the least number of HR from only those seasons with over 100 games played.

avg_batting_avg_aliased_as_career_average

Select the average, AVG, of Ruth's batting averages. The header of the result would be AVG(AVG) which is quite confusing, so provide an alias of career_average.

total_years_and_hits_per_team

Select the team and the total number of years and hits, but represent the results on a per team basis. (Hint: you will need to sort the result with a certain clause...)

total_years_and_hr_per_team_ordered_by_hr

The previous query returns Babe Ruth's Boston stats first. However, the overwhelming majority of Ruth's career statistics came when he played for the NY Yankees. Shouldn't we list Ruth's NY stats first? Write the previous query again, but this time we want Babe Ruth's total HRs instead of his total hits. Make sure that the resulting data set lists Babe Ruth's stats as a Yankee first.

Hint: You will need to chain another sorting clause after GROUP BY.

years_with_on_base_over_300

We want to know the years in which Ruth successfully reached base over 300 times. We need to add hits and BB to calculate how many times Ruth reached base. Simply add the two columns together (ie: SELECT hits + BB FROM ...) and give this value an alias of on_base. Select the year and on_base for only those years with an on_base over 300.

Hint: WHERE won't work here!

Summary

Well done! In this lab we continued adding complexity to our SQL statements and wrote aggregate functions. We were able to build our queries from giving us totals and averages to showing us the total years and homeruns earned by team as well as calculating Babe Ruth's total on base and then selecting only years that met a minimum value of our calculated on base attribute.