Counting total number of records in a table:
SELECT COUNT(*) FROM table_name
The below query returns the number of values (NULL values will not be counted) of the specified column:
SELECT COUNT(column_name) FROM table-name
Counting the number of distinct values of the specified column:
SELECT COUNT(DISTINCT column-name) FROM table-name
The following SQL statement would return the name of the department and the number of employees (in the associated department) that make over $12,000 / year.
SELECT department, COUNT(*) as "Employee COunt - Number of employees"
WHERE salary > 12000
GROUP BY department;
Some more useful stuff on SQL Count
SQL COUNT( NULLIF( .. ) ) Is Totally Awesome
SQL COUNT NULLIF
Counting the number of columns in a table
SQL Server - Counting the number of columns in a table