COUNT returns the total count of records in a column or the count for DISTINCT (unique) values selected by the query. : Count « Aggregate Functions « SQL Server / T-SQL Tutorial





All NULL values are ignored in the total count.


9> CREATE TABLE sales(
10>    stor_id        char(4)           NOT NULL,
11>    ord_num        varchar(20)       NOT NULL,
12>    ord_date       datetime          NOT NULL,
13>    qty            smallint          NOT NULL,
14>    payterms       varchar(12)       NOT NULL,
15>    title_id       varchar(80)
16> )
17> GO
1> insert sales values('1', 'QA7442.3', '09/13/94', 75, 'ON Billing','1')
2> insert sales values('2', 'D4482',    '09/14/94', 10, 'Net 60',    '1')
3> insert sales values('3', 'N914008',  '09/14/94', 20, 'Net 30',    '2')
4> insert sales values('4', 'N914014',  '09/14/94', 25, 'Net 30',    '3')
5> insert sales values('5', '423LL922', '09/14/94', 15, 'ON Billing','3')
6> insert sales values('6', '423LL930', '09/14/94', 10, 'ON Billing','2')
7> GO

(1 rows affected)

(1 rows affected)

(1 rows affected)

(1 rows affected)

(1 rows affected)

(1 rows affected)
1>
2>
3> select COUNT(qty) from sales;
4> GO

-----------
          6

(1 rows affected)
1>
2> drop table sales;
3>
4> GO
1>










9.3.Count
9.3.1.COUNT returns the total count of records in a column or the count for DISTINCT (unique) values selected by the query.
9.3.2.COUNT(*) returns the total count of all records (rows) in the column, including NULL values of selected records by the query.
9.3.3.Count function with column alias
9.3.4.Counting unique values.
9.3.5.A common mistake with DISTINCT is to code the DISTINCT statement before the COUNT statement.
9.3.6.Counting values including NULL values.
9.3.7.Using ISNULL to count all values including NULLs.
9.3.8.Count table row in dynamic sql