IsDescendantOf (Database Engine)

Article
09/03/2024

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance

Returns true if this is a descendant of parent.

Syntax

-- Transact-SQL syntax  
child. IsDescendantOf ( parent )

-- CLR syntax  
SqlHierarchyId IsDescendantOf (SqlHierarchyId parent )

Arguments

parent
The hierarchyid node for which the IsDescendantOf test should be performed.

Return Types

SQL Server return type:bit

CLR return type:SqlBoolean

Remarks

Returns true for all the nodes in the sub-tree rooted at parent, and false for all other nodes.

Parent is considered its own descendant.

Examples

A. Using IsDescendantOf in a WHERE clause

The following example returns a manager and the employees that report to the manager:

DECLARE @Manager hierarchyid  
SELECT @Manager = OrgNode FROM HumanResources.EmployeeDemo  
  WHERE LoginID = 'adventure-works\dylan0'  
  
SELECT * FROM HumanResources.EmployeeDemo  
WHERE OrgNode.IsDescendantOf(@Manager) = 1

B. Using IsDescendantOf to evaluate a relationship

The following code declares and populates three variables. It then evaluates the hierarchical relationship and returns one of two printed results based on the comparison:

DECLARE @Manager hierarchyid, @Employee hierarchyid, @LoginID nvarchar(256)  
SELECT @Manager = OrgNode FROM HumanResources.EmployeeDemo  
WHERE LoginID = 'adventure-works\terri0' ;  
  
SELECT @Employee = OrgNode, @LoginID = LoginID FROM HumanResources.EmployeeDemo  
  WHERE LoginID = 'adventure-works\rob0'  
  
IF @Employee.IsDescendantOf(@Manager) = 1  
   BEGIN  
    PRINT 'LoginID ' + @LoginID + ' is a subordinate of the selected Manager.'  
   END  
ELSE  
   BEGIN  
    PRINT 'LoginID ' + @LoginID + ' is not a subordinate of the selected Manager.' ;  
   END

C. Calling a common language runtime method

The following code snippet calls the IsDescendantOf() method.

this.IsDescendantOf(Parent)

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