While count finds the number of non-null values in an expression, count(*) finds the total number of rows in a table. This statement finds the total number of books:
select count(*) from titles
------------------ 18 (1 row affected)
count(*) returns the number of rows in the specified table without eliminating duplicates. It counts each row, including those containing null values.
Like other aggregate functions, you can combine count(*) with other aggregates in the select list, with where clauses, and so on:
select count(*), avg(price) from titles where advance > 1000
---------- --------- 15 14.42 (1 row affected)
