DB2 存儲過程中有時候會在一個遊標循環內部，還有一個遊標循環。
第二個遊標循環中，也會使用到第一個遊標循環中的值作爲輸入參數，來獲取第二個循環結果。
1 遊標循環結構是這樣的：
FOR txn as curs CURSOR WITH HOLD FOR
select fields_name from table where condition group by condition order by fields
DO
FOR conn as
select fields_name from table where txn.fields_name group by condition order by fields
DO
To Do the job in here
END FOR;
END FOR;
在 To Do the job 位置可以 組織返回結果。這樣就可以嵌套循環了。
同樣在To Do the job 位置還可以加入select into語句。
如下：
select count(chgpntcd), sum(kwhconsumed), sum(duration) into totalKWHours, totalKWHours, totalKWHours from ntwpt.rechtxnhis；
set Response = totalKWHours || totalKWHours || totalKWHours;
2 同樣的也可以在第一個循環裏面並列加入多個二級For循環：
FOR txn as curs CURSOR WITH HOLD FOR
select fields_name from table where condition group by condition order by fields
DO
//第一個並列二級循環
FOR conn as
select fields_name from table where txn.fields_name group by condition order by fields
DO
To Do the job in here
END FOR;
//第 二個並列二級循環
FOR conn as
select fields_name from table where txn.fields_name group by condition order by fields
DO
To Do the job in here
END FOR;
END FOR;