COUNT()
The COUNT()
aggregate function returns the total number of rows that match the specified criteria.
Syntax
SELECT COUNT(column_name)FROM table_name;
COUNT()
is a function that takes the name of a column as an argument and counts the number of rows where the column is not NULL
.
Note: A column name of the table can also be used instead of *
. Unlike COUNT(*)
, this variation COUNT(column_name)
will not count NULL
values in that column.
Example
Suppose there’s an employees
table with the following values:
name | salary | experience |
---|---|---|
Michael | 80000 | 14 |
Pam | 41500 | 2 |
Jim | 45000 | 4 |
Dwight | 55000 | 8 |
To find the total number of employees who have less than 5 years of experience, the given query can be used:
SELECT COUNT(*)FROM employeesWHERE experience < 5;
The result would be:
COUNT(*) |
---|
2 |
Contributors
- Anonymous contributors