SELECT ip FROM dbo.IPs JOIN dbo.IPPatterns ON ip LIKE pattern ORDER BY in Visual C#

Creation Denso QR Bar Code in Visual C# SELECT ip FROM dbo.IPs JOIN dbo.IPPatterns ON ip LIKE pattern ORDER BY

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CAST(SUBSTRING(ip, CAST(SUBSTRING(ip, CAST(SUBSTRING(ip, CAST(SUBSTRING(ip, s1, s2, s3, s4, l1) l2) l3) l4) AS AS AS AS TINYINT), TINYINT), TINYINT), TINYINT);

This query generates the following output:

ip --------------3.107.2.4 3.107.3.169 3.107.104.172 22.20.2.77 22.107.202.123 22.156.9.91 22.156.89.32 131.33.2.201 131.33.2.202 131.107.2.201

The problem with this solution is that it s not very ef cient, and it doesn t work in the more generic cases of lists where you have an unknown number of elements. Interestingly, the canonical representation of HIERARCHYID values in SQL Server 2008 is also a separated list of numbers. Within a level you can have values separated by dots, and between levels the values are separated by slashes. With this in mind, you can handle the task at hand by concatenating a slash before and after the IP address, then sorting the rows after converting the result to the HIERARCHYID data type, like so:

SELECT ip FROM dbo.IPs ORDER BY CAST('/' + ip + '/' AS HIERARCHYID);

This solution works just as well with the more generic case of the problem. To demonstrate this, rst create and populate the table T1 by running the following code:

SET NOCOUNT ON; USE tempdb; IF OBJECT_ID('dbo.T1', 'U') IS NOT NULL DROP TABLE dbo.T1; CREATE TABLE dbo.T1 ( id INT NOT NULL IDENTITY PRIMARY KEY, val VARCHAR(500) NOT NULL ); GO INSERT INTO dbo.T1(val) VALUES ('100'), ('7,4,250'), ('22,40,5,60,4,100,300,478,19710212'), ('22,40,5,60,4,99,300,478,19710212'), ('22,40,5,60,4,99,300,478,9999999'), ('10,30,40,50,20,30,40'),

('7,4,250'), ('-1'), ('-2'), ('-11'), ('-22'), ('-123'), ('-321'), ('22,40,5,60,4,-100,300,478,19710212'), ('22,40,5,60,4,-99,300,478,19710212');

As you can see, the lists in the table have varying numbers of elements. Note that because the separator used in these lists is a comma, you need to replace the separators by slashes or dots before converting to the HIERARCHYID data type. Here s the solution query that sorts the lists by the numeric values of the elements:

SELECT id, val FROM dbo.T1 ORDER BY CAST('/' + REPLACE(val, ',', '/') + '/' AS HIERARCHYID);

This query generates the following output:

id ----------13 12 11 10 9 8 7 2 6 14 15 5 4 3 1 val ------------------------------------321 -123 -22 -11 -2 -1 7,4,250 7,4,250 10,30,40,50,20,30,40 22,40,5,60,4,-100,300,478,19710212 22,40,5,60,4,-99,300,478,19710212 22,40,5,60,4,99,300,478,9999999 22,40,5,60,4,99,300,478,19710212 22,40,5,60,4,100,300,478,19710212 100

Note that you can create a computed persisted column in the table based on this expression and index that column. Such an index can support a request to sort the data without the need for an explicit sort operation in the query s execution plan.

nd Joe Celko s coverage of nested sets in his book Joe Celko s Trees and Hierarchies in SQL for Smarties (Morgan-Kaufmann, 2004).

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The main advantages of the nested sets solution are simple and fast queries, which I ll describe later, and no level limit. Unfortunately, however, with large data sets the solution s practicality is usually limited to static trees. For dynamic environments, the solution is limited to small trees (or forests of small trees). Instead of representing a tree as an adjacency list (parent-child relationship), this solution models the tree relationships as nested sets. A parent is represented in the nested sets model as a containing set, and a child is represented as a contained set. Set containment relationships are represented with two integer values assigned to each set: left and right. For all sets, a set s left value is smaller than all contained sets left values, and a set s right value is higher than all contained sets right values. Naturally, this containment relationship is transitive in terms of n-level relationships (ancestor/descendant). The queries are based on these nested sets relationships. Logically, it s as if a set spreads two arms around all its contained sets.

Figure 12-9 provides a graphical visualization of the Employees hierarchy with the left and right values assigned to each employee.