Populating a Hierarchical Table Using Hierarchical Methods

AdventureWorks has 8 employees working in the Marketing department. The employee hierarchy looks like this:

David, EmployeeID 6, is the Marketing Manager. Three Marketing Specialists report to David:

• Sariya, EmployeeID 46

• John, EmployeeID 271

• Jill, EmployeeID 119

Marketing Assistant Wanida (EmployeeID 269), reports to Sariya, and Marketing Assistant Mary (EmployeeID 272), reports to John.

To insert the root of the hierarchy tree

1. The following example inserts David the Marketing Manager into the table at the root of the hierarchy. The OrdLevel column is a computed column. Therefore, it is not part of the INSERT statement. This first record uses the GetRoot() method to populate this first record as the root of the hierarchy.

   INSERT HumanResources.EmployeeOrg (OrgNode, EmployeeID, EmpName, Title)
   VALUES (hierarchyid::GetRoot(), 6, 'David', 'Marketing Manager') ;
   GO
   

2. Execute the following code to examine initial row in the table:

   SELECT OrgNode.ToString() AS Text_OrgNode, 
   OrgNode, OrgLevel, EmployeeID, EmpName, Title 
   FROM HumanResources.EmployeeOrg ;
   

   Here is the result set.

   Text_OrgNode OrgNode OrgLevel EmployeeID EmpName Title
   ------------ ------- -------- ---------- ------- -----------------
   /            Ox      0        6          David   Marketing Manager
   

As in the previous lesson, we use the ToString() method to convert the hierarchyid data type to a format that is more easily understood.

To insert a subordinate employee

1. Sariya reports to David. To insert Sariya's node, you must create an appropriate OrgNode value of data type hierarchyid. The following code creates a variable of data type hierarchyid and populates it with the root OrgNode value of the table. Then uses that variable with the GetDescendant() method to insert row that is a subordinate node. GetDescendant takes two arguments. Review the following options for the argument values:

   • If parent is NULL, GetDescendant returns NULL.

   • If parent is not NULL, and both child1 and child2 are NULL, GetDescendant returns a child of parent.

   • If parent and child1 are not NULL, and child2 is NULL, GetDescendant returns a child of parent greater than child1.

   • If parent and child2 are not NULL and child1 is NULL, GetDescendant returns a child of parent less than child2.

   • If parent, child1, and child2 are all not NULL, GetDescendant returns a child of parent greater than child1 and less than child2.

   The following code uses the (NULL, NULL) arguments of the root parent because there are not yet any rows in the table except the root. Execute the following code to insert Sariya:

   DECLARE @Manager hierarchyid 
   SELECT @Manager = hierarchyid::GetRoot()
   FROM HumanResources.EmployeeOrg ;
   
   INSERT HumanResources.EmployeeOrg (OrgNode, EmployeeID, EmpName, Title)
   VALUES
   (@Manager.GetDescendant(NULL, NULL), 46, 'Sariya', 'Marketing Specialist') ; 
   

2. Repeat the query from the first procedure to query the table and see how the entries appear:

   SELECT OrgNode.ToString() AS Text_OrgNode, 
   OrgNode, OrgLevel, EmployeeID, EmpName, Title 
   FROM HumanResources.EmployeeOrg ;
   

   Here is the result set.

   Text_OrgNode OrgNode OrgLevel EmployeeID EmpName Title
   ------------ ------- -------- ---------- ------- -----------------
   /            Ox      0        6          David   Marketing Manager
   /1/          0x58    1        46         Sariya  Marketing Specialist
   

To create a procedure for entering new nodes

1. To simplify entering data, create the following stored procedure to add employees to the EmployeeOrg table. The procedure accepts input values about the employee being added. This includes the EmployeeID of the new employee's manager, the new employee's EmployeeID number, and their first name and title. The procedure uses GetDescendant() and also the GetAncestor() method. Execute the following code to create the procedure:

   CREATE PROC AddEmp(@mgrid int, @empid int, @e_name varchar(20), @title varchar(20)) 
   AS 
   BEGIN
      DECLARE @mOrgNode hierarchyid, @lc hierarchyid
      SELECT @mOrgNode = OrgNode 
      FROM HumanResources.EmployeeOrg 
      WHERE EmployeeID = @mgrid
      SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
      BEGIN TRANSACTION
         SELECT @lc = max(OrgNode) 
         FROM HumanResources.EmployeeOrg 
         WHERE OrgNode.GetAncestor(1) =@mOrgNode ;
   
         INSERT HumanResources.EmployeeOrg (OrgNode, EmployeeID, EmpName, Title)
         VALUES(@mOrgNode.GetDescendant(@lc, NULL), @empid, @e_name, @title)
      COMMIT
   END ;
   GO
   

2. The following example adds the remaining 4 employees that report directly or indirectly to David.

   EXEC AddEmp 6, 271, 'John', 'Marketing Specialist' ;
   EXEC AddEmp 6, 119, 'Jill', 'Marketing Specialist' ;
   EXEC AddEmp 46, 269, 'Wanida', 'Marketing Assistant' ;
   EXEC AddEmp 271, 272, 'Mary', 'Marketing Assistant' ;
   

3. Again, execute the following query examine the rows in the EmployeeOrg table:

   SELECT OrgNode.ToString() AS Text_OrgNode, 
   OrgNode, OrgLevel, EmployeeID, EmpName, Title 
   FROM HumanResources.EmployeeOrg ;
   GO
   

   Here is the result set.

   Text_OrgNode OrgNode OrgLevel EmployeeID EmpName Title
   ------------ ------- -------- ---------- ------- -----------------
   /            Ox      0        6          David   Marketing Manager
   /1/          0x58    1        46         Sariya  Marketing Specialist
   /1/1/        0x5AC0  2        269        Wanida  Marketing Assistant
   /2/          0x68    1        271        John    Marketing Specialist
   /2/1/        0x6AC0  2        272        Mary    Marketing Assistant
   /3/          0x78    1        119        Jill    Marketing Specialist
   

The table is now fully populated with the Marketing organization.

Next Task in Lesson

Querying a Hierarchical Table Using Hierarchy Methods