我有这个问题:
SELECT * FROM PATIENT_MED_SPEC
给出了这个结果:
NUM_MALADE| NUM_MED| SPECIALITE ----------+--------+------------ 3 53 Traumatologue 3 85 Anesthésiste 3 126 Radiologue 6 34 Pneumologue 6 85 Anesthésiste 6 114 Traumatologue 6 135 Anesthésiste 13 4 Orthopédiste 13 8 Cardiologue 13 114 Traumatologue 21 19 Traumatologue 21 64 Radiologue 21 135 Anesthésiste 23 4 Orthopédiste 23 8 Cardiologue 23 88 Cardiologue
我希望使用count
和group by
子句
NUM_MALADE| count_MED| count_SPEc ----------+----------+------------ 3 3 3 6 4 3 13 3 3 21 3 3 23 3 2
即每MALADE
(患者)我们都会计算MEDECIN
(医生)号码和SPECIALITES
有关的人数
答案 0 :(得分:1)
您可以使用COUNT DISTINCT
:
SELECT MALADE, COUNT(*) AS count_MED, COUNT(DISTINCT SPECIALITE) AS num_SPEC
FROM PATIENT_MED_SPEC
GROUP BY MALADE