--- title: SQL COUNT Aggregate Function --- ## SQL COUNT Aggregate Function The COUNT operator is usually used in combination with a GROUP BY clause. It is one of the SQL "aggregate" functions, which include AVG (average) and SUM. This function will count the number of rows and return that count as a column in the result set. Here are examples of what you would use COUNT for: * Counting all rows in a table (no group by required) * Counting the totals of subsets of data (requires a Group By section of the statement) For reference, here is the current data for all the rows in our example student database. ```sql select studentID, FullName, programOfStudy, sat_score from student; -- all records with fields of interest ``` Result : ```text +-----------+------------------+----------------+-----------+ | studentID | FullName | programOfStudy | sat_score | +-----------+------------------+----------------+-----------+ | 1 | Monique Davis | Literature | 400 | | 2 | Teri Gutierrez | Programming | 800 | | 3 | Spencer Pautier | Programming | 1000 | | 4 | Louis Ramsey | Programming | 1200 | | 5 | Alvin Greene | Photography | 1400 | | 6 | Sophie Freeman | Photography | 1600 | | 7 | Maximo Smith | Photography | 1800 | | 8 | Michael Roach | Literature | 800 | +-----------+------------------+----------------+-----------+ ``` * This SQL statement provides a count of all rows. Note that you can give the resulting COUNT column a name using "AS". ```sql select count(*) AS studentCount from student; -- count of all records ``` Result : ```text +--------------+ | studentCount | +--------------+ | 8 | +--------------+ ``` * Here we get a count of students in each field of study. ```sql select programOfStudy, count(*) AS studentCount from the student table with a group by programOfStudy; ``` Result : ```text +----------------+--------------+ | programOfStudy | studentCount | +----------------+--------------+ | Literature | 2 | | photography | 3 | | programming | 3 | +----------------+--------------+ ``` * Here we get a count of students with the same SAT scores. ```sql select sat_score, count(*) AS studentCount from the student table with a group by sat_score; ``` Result : ```text +-----------+--------------+ | sat_score | studentCount | +-----------+--------------+ | 400 | 1 | | 800 | 2 | | 1000 | 1 | | 1200 | 1 | | 1400 | 1 | | 1600 | 1 | | 1800 | 1 | +-----------+--------------+ ``` * Here is an example using the campaign funds table. This is a sum total of the dollars in each transaction and the number of contributions for each political party during the 2016 US Presidential Campaign. ```sql select Specific_Party, Election_Year, format(sum(Total_$),2) AS contribution$Total, count(*) AS numberOfContributions from combined_party_data group by Specific_Party,Election_Year having Election_Year = 2016; ``` Result : ```text +----------------+---------------+--------------------+-----------------------+ | Specific_Party | Election_Year | contribution$Total | numberOfContributions | +----------------+---------------+--------------------+-----------------------+ | DEMOCRATIC | 2016 | 833,592,846.09 | 361 | | REPUBLICAN | 2016 | 676,149,662.07 | 1247 | +----------------+---------------+--------------------+-----------------------+ ``` As with all of these things there is much more to it, so please see the manual for your database manager and have fun trying different tests yourself.