SQL 2005 case ステートメントのようにキーワードを使用できますか

これを試してください

SELECT CASE 
           WHEN ColumnName = 'value1' THEN 'answer1'
           WHEN ColumnName = 'value2' THEN 'answer2'
           WHEN ColumnName LIKE '%TEST%' THEN 'answer3'
       END AS Answer
FROM TableName

実行できる例

SELECT name,CASE 
           WHEN Name = 'sysobjects' THEN 'answer1'
           WHEN Name = 'syscols' THEN 'answer2'
           WHEN Name LIKE '%p%' THEN 'answer3'
           ELSE 'unknown'
       END AS Answer
FROM sysobjects