SQL: Alias Column Name for Use in CASE Statement

Question

Is it possible to alias a column name and then use that in a CASE statement? For example,

SELECT col1 as a, CASE WHEN a = \'test\' THEN \'yes\' END as value          


        

Answer 1

@OMG Ponies - One of my reasons of not using the following code

SELECT t.col1 as a, 
     CASE WHEN t.col1 = 'test' THEN 'yes' END as value 
FROM TABLE t;

can be that the t.col1 is not an actual column in the table. For example, it can be a value from a XML column like

Select XMLColumnName.value('(XMLPathOfTag)[1]', 'varchar(max)') 
as XMLTagAlias from Table