COUNT (TSQL Function)
Returns the count of the column values.
Syntax
COUNT ( expression )
COUNT ( * )
Arguments
- expression
- is an expression of any type.
Return Types
Returns int
.
Remarks
NULL values in the expression are ignored.
COUNT(*)
counts all expressions, including NULL values.
Examples
DECLARE @t TABLE (
id INT NOT NULL PRIMARY KEY,
name VARCHAR(30),
birthdate DATE,
children TINYINT
);
INSERT INTO @t VALUES (10, 'John', '19700301', 1),
(20, 'Fred', '20021123', NULL),
(40, 'Alex', '19950712', 2),
(50, 'Maria', '19700322', 0),
(30, 'Alice', '19950101', NULL),
(15, NULL, '19950101', 5);
SELECT YEAR(birthdate), SUM(children), COUNT(*), COUNT(children)
FROM @t
GROUP BY YEAR(birthdate)
ORDER BY YEAR(birthdate);
The result is:
$g$0 |$sum$1 |$count$2 |$count$3 |
-----------+--------------------+-----------+-----------+
1970| 1| 2| 2|
1995| 7| 3| 2|
2002| <NULL>| 1| 0|
(3 row(s) affected)