List the aggregate functions supported by SQL

SQL offers five built in aggregate functions:

(i) Average: avg

returns the average value of a given column.

Example: Find the average account balance.

Solution: Select avg(balance) from account.

(ii) Minimum: min

returns the smallest value in a given column.

Example: Find the minimum account balance at the perryridge branch.

Solution: select min(balance) from account where branch-name = “perryridge”.

(iii) Maximum: max

returns the largest value in a given column.

Example: Find the largest account balance in the bank.

Solution: select max(balance) from account.

(iv) Total: sum

returns the sum of the numeric values in a given column.

Example: Find the total account balance of Mirpur branch.

Solution: select sum(balance) from account where branch-name = “Mirpur”.

(v) Count: count

returns the total number of values in a given column.

Example: Find the number of tuples in the customer relation.

Solution: select count(*) from customer.