SQL Server 2012 : Ordering the Result Set (part 2) - Specifying the ORDER BY Using Column Aliases, Using the Column Ordinal Position , ORDER BY and Collation

Specifying the ORDER BY Using Column Aliases

Alternatively, you can use a column alias to specify the columns used in the ORDER BY clause. This is the preferred method for sorting by an expression because it makes the code easier to read. This example sorts in descending order, rather than the default ascending order:

USE AdventureWorks
SELECT LastName + ‘, ‘ + FirstName as FullName
 FROM Person.Person
 ORDER BY FullName DESC;

Result:

FullName
-------------
Zwilling, Michael
Zwilling, Michael
Zukowski, Jake
Zugelder, Judy
Zubaty, Patricia
Zubaty, Carla
Zimprich, Karin
. . .

An alias is allowed in the ORDER BY clause but not the WHERE clause because the WHERE clause is logically executed prior to processing columns and expressions. The ORDER BY clause follows the assembling of the columns and aliases, so it can use column aliases.

Using the Column Ordinal Position

You can use the ordinal number of the column (column position number) to indicate the ORDER BY columns, but don't do this. If the select columns are changed or their order changes, the sort order also changes.

One case for which it's not necessarily a horrid practice to use the ordinal number to specify the sort is for complex union queries.

The following query demonstrates sorting by ordinal position:

USE AdventureWorks
SELECT LastName + ‘, ‘ + FirstName as FullName
 FROM Person.Person
 ORDER BY 1;

Result:

FullName
----------------------
Abbas, Syed
Abel, Catherine
Abercrombie, Kim
. . .

ORDER BY and Collation

SQL Server's collation order is vital to sorting data. In addition to determining the alphabet, the collation order also determines whether accents, case, and other alphabet properties are considered in the sort order. For example, if the collation is case-sensitive, then the uppercase letters are sorted before the lowercase letters. The following function reports the installed collation options and the current collation server property:

SELECT * FROM fn_helpcollations();

Result:

name         description
--------------------- -------------------------
Albanian_BIN     Albanian, binary sort
Albanian_CI_AI    Albanian, case-insensitive,
           accent-insensitive,
           kanatype-insensitive, width-insensitive
Albanian_CI_AI_WS   Albanian, case-insensitive,
           accent-insensitive,
           kanatype-insensitive, width-sensitive
. . .
SQL_Latin1_General_CP1_CI_AI
           Latin1-General,case-insensitive,
           accent-insensitive,
           kanatype-insensitive, width-insensitive
           for Unicode Data, SQL Server Sort Order
           54 on Code Page 1252 for non-Unicode
           Data
. . .

The following query reports the current server collation:

SELECT SERVERPROPERTY('Collation') AS ServerCollation;

Result:

ServerCollation
------------------------
SQL_Latin1_General_CP1_CI_AS

Although the server collation setting is determined during setup, you can set the collation property for a database or a column using the COLLATE keyword. The following code changes the AdventureWorks database collation so that it becomes case-sensitive:

CREATE DATABASE CollateChange
 GO
 ALTER DATABASE CollateChange
 COLLATE SQL_Latin1_General_CP1_CS_AS;
 GO
 SELECT DATABASEPROPERTYEX('CollateChange','Collation')
 AS DatabaseCollation;

Result:

DatabaseCollation
----------------------------------
SQL_Latin1_General_CP1_CS_AS

Not only can SQL Server set the collation at the server, database, and column levels, collation can even be set at the individual query level. The following query sorts according to the Danish collation, without regard to case or accents:

Use AdventureWorks
SELECT *
 FROM Production.Product
 ORDER BY Name
  COLLATE Danish_Norwegian_CI_AI;

Not all queries need to be sorted, but for those that do, the ORDER BY clause combined with the many possible collations yields tremendous flexibility in sorting the result set.

• At the end of the statement preceding a common table expression (CTE)
• At the end of a MERGE statement

• Between the END TRY and BEGIN CATCH.
• Between the IF condition and the BEGIN.
• Don't mix GO and the semicolon on the same line.