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FIRST_VALUE (Transact-SQL)

SQL Server 2012

Returns the first value in an ordered set of values in SQL Server 2012.

Topic link icon Transact-SQL Syntax Conventions

FIRST_VALUE ( [scalar_expression ] ) 
    OVER ( [ partition_by_clause ] order_by_clause [ rows_range_clause ] )
scalar_expression

Is the value to be returned. scalar_expression can be a column, subquery, or other arbitrary expression that results in a single value. Other analytic functions are not permitted.

OVER ( [ partition_by_clause ] order_by_clause [ rows_range_clause ] )

partition_by_clause divides the result set produced by the FROM clause into partitions to which the function is applied. If not specified, the function treats all rows of the query result set as a single group. order_by_clause determines the logical order in which the operation is performed. order_by_clause is required. rows_range_clause further limits the rows within the partition by specifying start and end points. For more information, see OVER Clause (Transact-SQL).

Is the same type as scalar_expression.

A. Using FIRST_VALUE over a query result set

The following example uses FIRST_VALUE to return the name of the product that is the least expensive in a given product category.

USE AdventureWorks2012;
GO
SELECT Name, ListPrice, 
       FIRST_VALUE(Name) OVER (ORDER BY ListPrice ASC) AS LeastExpensive 
FROM Production.Product
WHERE ProductSubcategoryID = 37;

Here is the result set.

Name                    ListPrice             LeastExpensive
----------------------- --------------------- --------------------
Patch Kit/8 Patches     2.29                  Patch Kit/8 Patches
Road Tire Tube          3.99                  Patch Kit/8 Patches
Touring Tire Tube       4.99                  Patch Kit/8 Patches
Mountain Tire Tube      4.99                  Patch Kit/8 Patches
LL Road Tire            21.49                 Patch Kit/8 Patches
ML Road Tire            24.99                 Patch Kit/8 Patches
LL Mountain Tire        24.99                 Patch Kit/8 Patches
Touring Tire            28.99                 Patch Kit/8 Patches
ML Mountain Tire        29.99                 Patch Kit/8 Patches
HL Road Tire            32.60                 Patch Kit/8 Patches
HL Mountain Tire        35.00                 Patch Kit/8 Patches

B. Using FIRST_VALUE over partitions

The following example uses FIRST_VALUE to return the employee with the fewest number of vacation hours compared to other employees with the same job title. The PARTITION BY clause partitions the employees by job title and the FIRST_VALUE function is applied to each partition independently. The ORDER BY clause specified in the OVER clause determines the logical order in which the FIRST_VALUE function is applied to the rows in each partition. The ROWS UNBOUNDED PRECEDING clause specifies the starting point of the window is the first row of each partition.

USE AdventureWorks2012; 
GO
SELECT JobTitle, LastName, VacationHours, 
       FIRST_VALUE(LastName) OVER (PARTITION BY JobTitle 
                                   ORDER BY VacationHours ASC
                                   ROWS UNBOUNDED PRECEDING
                                  ) AS FewestVacationHours
FROM HumanResources.Employee AS e
INNER JOIN Person.Person AS p 
    ON e.BusinessEntityID = p.BusinessEntityID
ORDER BY JobTitle;

Here is a partial result set.

JobTitle                            LastName                  VacationHours FewestVacationHours
----------------------------------- ------------------------- ------------- -------------------
Accountant                          Moreland                  58            Moreland
Accountant                          Seamans                   59            Moreland
Accounts Manager                    Liu                       57            Liu
Accounts Payable Specialist         Tomic                     63            Tomic
Accounts Payable Specialist         Sheperdigian              64            Tomic
Accounts Receivable Specialist      Poe                       60            Poe
Accounts Receivable Specialist      Spoon                     61            Poe
Accounts Receivable Specialist      Walton                    62            Poe
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