DB2数字类型转换成字符串类型,例：ORACLE与DB2

select 1/3 from sysibm.sysdummy1; 如果想要最初的语句1/3得到非零值。可以使用如下方法：
(1) select 1.0/3 from sysibm.sysdummy1; ---得到小数值 结果： --0.333333333333333333333333333333(2) select 1/3.0 from sysibm.sysdummy1; ----同样得到小数值 结果： --0.3333333333333333333(3) select cast(1 as float)/3 from sysibm.sysdummy1; --使用cast将1转为float型，然后再才除以3. 结果：0.3333333333333333(4) select dec(1,10,2)/3 from sysibm.sysdummy1; ---使用dec函数将1转换为decimal(10,2)，然后除以3 结果：0.33333333333333333333333 其实如果想要把2个数的商四舍五入保存两位小数，oracle中可以直接使用round函数即可：select round(a/b,2) from dual;而db2中却要绕几个弯才行：需要使用select dec(cast(a as float)/b+0.005,10,2) from sysibm.sysdummy1; 先用cast转换a为float型，然后运算，再使用+0.005作为四舍五入，然后再使用dec截取2位小数。或者：select cast(round(cast(a as float)/b,2) as decimal(10,2)) from sysibm.sysdummy1; 先使用cast转a为float，然后运算，再使用round四舍五入取2位小数，然后使用cast转换为decimal(10,2)型。
例如：1.Oracle数据库SQL语句转换成DB2数据库SQL语句a.Oracle SQL语句
select *
from (select t.device_name,
count(t.device_name) as num,
to_char(round(count(t.device_name) /
(select sum(aa)
from (select count(t.device_name) as aa
from EQUIPMENT_MONITORING t
where 1 = 1
and t.device_area = 'AA区'
group by t.device_name)) * 100,
2),
'990.99') || '%' as num_percent,
sum(trunc(t.deal_time - t.occa_time) * 24 * 60 * 60) as occur
from EQUIPMENT_MONITORING t
where 1 = 1
and t.device_area = 'AA区'
group by t.device_name) v
where v.occur <> 0;

b.DB2 SQL语句
select t.device_name,
count(t.device_name) as num,
CHAR(CAST(round(cast(count(t.device_name) as float) /
(select sum(aa)
from (select count(t.device_name) as aa
from EQUIPMENT_MONITORING t
where 1 = 1
and t.device_area = 'AA区'
group by t.device_name)) * 100,
2) as decimal(3, 2))) || '%' as num_percent,
sum(dec(t.deal_time - t.occa_time) * 24 * 60 * 60) as occur
from EQUIPMENT_MONITORING t
where 1 = 1
and t.device_area = 'AA区'
group by t.device_name;