? SELECT COUNT() in SQL

The COUNT() function returns the number of rows that match a specified condition or total rows in a table.

? Syntax:

SELECT COUNT(column_name) FROM table_name WHERE condition;

or to count all rows including those with NULL in a column:

SELECT COUNT(*) FROM table_name WHERE condition;

? Examples:

Count total rows in a table:

SELECT COUNT(*) AS total_employees FROM employees;

Count rows where salary is not NULL:

SELECT COUNT(salary) AS salary_count FROM employees;

Count employees in the 'Sales' department:

SELECT COUNT(*) AS sales_countFROM employeesWHERE department = 'Sales';

Count distinct departments:

SELECT COUNT(DISTINCT department) AS unique_departments FROM employees;

? Notes:

• COUNT(*) counts all rows regardless of NULLs.

• COUNT(column_name) counts non-NULL values in that column.

• COUNT(DISTINCT column_name) counts unique non-NULL values.

Want me to show COUNT() with GROUP BY or joins?