碰到一个oracle汇总的很奇怪的问题,求解!
按学校汇总所有课程的总数据,课程编码要唯一
COURSETYPE 为1,2,3分别代表A类课, B类课,C类课)
SELECT count(distinct trim(COURSECODE)) FROM TB_XIAONEIZHUANRENJIAOSHISKQK WHERE COURSETYPE in(1,2,3) AND
COLLEGESID='4028813b307927aa01307927b6030001';
总数为390
SELECT count(distinct trim(COURSECODE)) FROM TB_XIAONEIZHUANRENJIAOSHISKQK WHERE
(COLLEGESID='4028813b307927aa01307927b6030001'
and COURSETYPE=1)
总数为186
SELECT count(distinct trim(COURSECODE)) FROM TB_XIAONEIZHUANRENJIAOSHISKQK WHERE COURSETYPE=2 AND
COLLEGESID='4028813b307927aa01307927b6030001';
总数为239
SELECT count(distinct trim(COURSECODE)) FROM TB_XIAONEIZHUANRENJIAOSHISKQK WHERE COURSETYPE=3 AND
COLLEGESID='4028813b307927aa01307927b6030001'
总数为 22
为什么A+B+C的总数为447不等于390啊?
困扰了很久,求大神解决!