COUNT (Transact-SQL)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
SQL analytics endpoint in Microsoft Fabric
Warehouse in Microsoft Fabric
This function returns the number of items found in a group. COUNT operates like the COUNT_BIG function. These functions differ only in the data types of their return values. COUNT always returns an int data type value. COUNT_BIG always returns a bigint data type value.
Transact-SQL syntax conventions
Syntax
Aggregation function syntax
COUNT ( { [ [ ALL | DISTINCT ] expression ] | * } )
Analytic function syntax
COUNT ( [ ALL ] { expression | * } ) OVER ( [ <partition_by_clause> ] )
Arguments
ALL
Applies the aggregate function to all values. ALL serves as the default.
DISTINCT
Specifies that COUNT returns the number of unique nonnull values.
expression
An expression of any type, except image, ntext, or text. COUNT doesn't support aggregate functions or subqueries in an expression.
*
Specifies that COUNT should count all rows to determine the total table row count to return. COUNT(*) takes no parameters and doesn't support the use of DISTINCT. COUNT(*) doesn't require an expression parameter because by definition, it doesn't use information about any particular column. COUNT(*) returns the number of rows in a specified table, and it preserves duplicate rows. It counts each row separately. This includes rows that contain null values.
OVER ( [ partition_by_clause ] [ order_by_clause ] [ ROW_or_RANGE_clause ] )
The partition_by_clause divides the result set produced by the FROM clause into partitions to which the COUNT function is applied. If not specified, the function treats all rows of the query result set as a single group. The order_by_clause determines the logical order of the operation. See OVER clause (Transact-SQL) for more information.
Return types
int NOT NULL when
ANSI_WARNINGSisON, however SQL Server will always treatCOUNTexpressions asint NULLin metadata, unless wrapped inISNULL.int NULL when
ANSI_WARNINGSisOFF.
Remarks
COUNT(*)withoutGROUP BYreturns the cardinality (number of rows) in the resultset. This includes rows comprised of all-NULLvalues and duplicates.COUNT(*)withGROUP BYreturns the number of rows in each group. This includesNULLvalues and duplicates.COUNT(ALL <expression>)evaluates expression for each row in a group, and returns the number of nonnull values.COUNT(DISTINCT *expression*)evaluates expression for each row in a group, and returns the number of unique, nonnull values.
COUNT is a deterministic function when used without the OVER and ORDER BY clauses. It is nondeterministic when used with the OVER and ORDER BY clauses. For more information, see Deterministic and nondeterministic functions.
ARITHABORT and ANSI_WARNINGS
When COUNT has a return value exceeding the maximum value of int (that is, 231-1 or 2,147,483,647), the COUNT function will fail due to an integer overflow. When COUNT overflows and both the ARITHABORT and ANSI_WARNINGS options are OFF, COUNT will return NULL. Otherwise, when either of ARITHABORT or ANSI_WARNINGS are ON, the query will abort and the arithmetic overflow error Msg 8115, Level 16, State 2; Arithmetic overflow error converting expression to data type int. will be raised. To correctly handle these large results, use COUNT_BIG instead, which returns bigint.
When both ARITHABORT and ANSI_WARNINGS are ON, you can safely wrap COUNT call-sites in ISNULL( <count-expr>, 0 ) to coerce the expression's type to int NOT NULL instead of int NULL. Wrapping COUNT in ISNULL means any overflow error will be silently suppressed, which should be considered for correctness.
Examples
A. Use COUNT and DISTINCT
This example returns the number of different titles that an Adventure Works Cycles employee can hold.
SELECT COUNT(DISTINCT Title)
FROM HumanResources.Employee;
GO
Here's the result set.
-----------
67
(1 row(s) affected)
B. Use COUNT(*)
This example returns the total number of Adventure Works Cycles employees.
SELECT COUNT(*)
FROM HumanResources.Employee;
GO
Here's the result set.
-----------
290
(1 row(s) affected)
C. Use COUNT(*) with other aggregates
This example shows that COUNT(*) works with other aggregate functions in the SELECT list. The example uses the AdventureWorks2022 database.
SELECT COUNT(*), AVG(Bonus)
FROM Sales.SalesPerson
WHERE SalesQuota > 25000;
GO
Here's the result set.
----------- ---------------------
14 3472.1428
(1 row(s) affected)
D. Use the OVER clause
This example uses the MIN, MAX, AVG and COUNT functions with the OVER clause, to return aggregated values for each department in the AdventureWorks2022 database HumanResources.Department table.
SELECT DISTINCT Name
, MIN(Rate) OVER (PARTITION BY edh.DepartmentID) AS MinSalary
, MAX(Rate) OVER (PARTITION BY edh.DepartmentID) AS MaxSalary
, AVG(Rate) OVER (PARTITION BY edh.DepartmentID) AS AvgSalary
, COUNT(edh.BusinessEntityID) OVER (PARTITION BY edh.DepartmentID) AS EmployeesPerDept
FROM HumanResources.EmployeePayHistory AS eph
JOIN HumanResources.EmployeeDepartmentHistory AS edh
ON eph.BusinessEntityID = edh.BusinessEntityID
JOIN HumanResources.Department AS d
ON d.DepartmentID = edh.DepartmentID
WHERE edh.EndDate IS NULL
ORDER BY Name;
Here's the result set.
Name MinSalary MaxSalary AvgSalary EmployeesPerDept
----------------------------- --------------------- --------------------- --------------------- ----------------
Document Control 10.25 17.7885 14.3884 5
Engineering 32.6923 63.4615 40.1442 6
Executive 39.06 125.50 68.3034 4
Facilities and Maintenance 9.25 24.0385 13.0316 7
Finance 13.4615 43.2692 23.935 10
Human Resources 13.9423 27.1394 18.0248 6
Information Services 27.4038 50.4808 34.1586 10
Marketing 13.4615 37.50 18.4318 11
Production 6.50 84.1346 13.5537 195
Production Control 8.62 24.5192 16.7746 8
Purchasing 9.86 30.00 18.0202 14
Quality Assurance 10.5769 28.8462 15.4647 6
Research and Development 40.8654 50.4808 43.6731 4
Sales 23.0769 72.1154 29.9719 18
Shipping and Receiving 9.00 19.2308 10.8718 6
Tool Design 8.62 29.8462 23.5054 6
(16 row(s) affected)
Examples: Azure Synapse Analytics and Analytics Platform System (PDW)
E. Use COUNT and DISTINCT
This example returns the number of different titles that an employee of a specific company can hold.
USE ssawPDW;
SELECT COUNT(DISTINCT Title)
FROM dbo.DimEmployee;
Here's the result set.
-----------
67
F. Use COUNT(*)
This example returns the total number of rows in the dbo.DimEmployee table.
USE ssawPDW;
SELECT COUNT(*)
FROM dbo.DimEmployee;
Here's the result set.
-------------
296
G. Use COUNT(*) with other aggregates
This example combines COUNT(*) with other aggregate functions in the SELECT list. It returns the number of sales representatives with an annual sales quota greater than $500,000, and the average sales quota of those sales representatives.
USE ssawPDW;
SELECT COUNT(EmployeeKey) AS TotalCount, AVG(SalesAmountQuota) AS [Average Sales Quota]
FROM dbo.FactSalesQuota
WHERE SalesAmountQuota > 500000 AND CalendarYear = 2001;
Here's the result set.
TotalCount Average Sales Quota
---------- -------------------
10 683800.0000
H. Use COUNT with HAVING
This example uses COUNT with the HAVING clause to return the departments of a company, each of which has more than 15 employees.
USE ssawPDW;
SELECT DepartmentName,
COUNT(EmployeeKey)AS EmployeesInDept
FROM dbo.DimEmployee
GROUP BY DepartmentName
HAVING COUNT(EmployeeKey) > 15;
Here's the result set.
DepartmentName EmployeesInDept
-------------- ---------------
Sales 18
Production 179
I. Use COUNT with OVER
This example uses COUNT with the OVER clause, to return the number of products contained in each of the specified sales orders.
USE ssawPDW;
SELECT DISTINCT COUNT(ProductKey) OVER(PARTITION BY SalesOrderNumber) AS ProductCount
, SalesOrderNumber
FROM dbo.FactInternetSales
WHERE SalesOrderNumber IN (N'SO53115',N'SO55981');
Here's the result set.
ProductCount SalesOrderID
------------ -----------------
3 SO53115
1 SO55981