我得到的一个单位进行的测试次数:如何用mysql中的空值替换丢失的记录?
select
date(START_DATE_TIME), product_id, BATCH_SERIAL_NUMBER, count(*)
from
(select START_DATE_TIME, product_id, uut_serial_number, BATCH_SERIAL_NUMBER
from uut_result
where START_DATE_TIME >= '2016-07-01 00:00:00'
and START_DATE_TIME <= '2016-07-07 23:59:59') as passtbl
group by date(START_DATE_TIME), product_id, batch_serial_number;
我取按天细分通过单位测试次数:
select
date(START_DATE_TIME), product_id, BATCH_SERIAL_NUMBER, count(*)
from
(select START_DATE_TIME, product_id, uut_serial_number, BATCH_SERIAL_NUMBER
from uut_result
where START_DATE_TIME >= '2016-07-01 00:00:00'
and START_DATE_TIME <= '2016-07-07 23:59:59'
and uut_status = 'passed') as passtbl
group by date(START_DATE_TIME), product_id, batch_serial_number;
什么,我发现是,有些单元根本没有任何通行记录,所以第二个查询返回的记录数比第一个少。这是打破后处理。有没有办法避免记录的缺失,并用空值或其他虚拟值替换它?