DB2 function: Null轉特定值 COALESCE

COALESCE 函數功能和ORACLE的NVL函數一樣,可將null值轉為特定預設值：
範例：
select coalesce(field,'noVal') from table

DB2的SQL Select command中使用CASE WHEN... THEN (IF...Then....Else)

範例：

SELECT
 (
    CASE WHEN (field1 = 'A') THEN 'ADD' 
         WHEN (field1 = 'D') THEN 'DEL'
    ELSE 'Error' 
    END
 ) AS codeName 
FROM codeMapping

[MS SQL , DB2]取得select結果列號 ROW_NUMBER( )

範例：
select ROW_NUMBER() OVER (PARTITION BY field1 ORDER BY field2 ASC) AS rownumber FROM table