SQL DML甲骨文查詢

Question

我試圖做這個查詢：西班牙醫院的名稱是什麼，在那裏工作超過2醫生，只爲該醫院工作。但結果並非我所期望的。

我有這些表：

CREATE TABLE Hospital (
    hid INT PRIMARY KEY, 
    name VARCHAR(127) UNIQUE, 
    country VARCHAR(127), 
    area INT 
); 
CREATE TABLE Doctor (
    ic INT PRIMARY KEY, 
    name VARCHAR(127), 
    date_of_birth INT, 
); 
CREATE TABLE Work (
    hid INT, 
    ic INT, 
    since INT, 
    FOREIGN KEY (hid) REFERENCES Hospital (hid), 
    FOREIGN KEY (ic) REFERENCES Doctor (ic), 
    PRIMARY KEY (hid,ic) 
); 

我試着用這樣的：

SELECT DISTINCT H.name 
FROM Doctor D, Work W, Hospital H 
WHERE D.bi = W.bi AND H.country = 'Spain' AND H.hid = W.hid AND W.ic = D.ic 
AND NOT EXISTS(
       SELECT * 
       FROM Hospital H2 
       WHERE H2.hid = W.hid 
) 
GROUP BY (H.name) 
HAVING COUNT(D.ic) > 2 
;  

感謝。

Answer 1

這應該適用於你，假設你指的是擁有> 2位專職醫生的醫院。

SQL> select * from hospital; 

     HID NAME     COUNTRY   AREA 
---------- -------------------- ------------ ---------- 
     1 General    Spain     1 
     2 Hospital 2   Spain     1 
     3 Hospital 3   Spain     1 

SQL> select * from doctor; 

     IC NAME     DATE_OF_BIRTH 
---------- -------------------- ------------- 
     1 Gregory House     1 
     2 Dougie Howser     1 
     3 Marie Curie      1 
     4 Dr Who       1 
     5 Dr Zeuss       1 

SQL> select * from work; 

     HID   IC  SINCE 
---------- ---------- ---------- 
     1   1   1 
     1   2   1 
     2   3   1 
     2   4   1 
     3   4   1 
     1   5   1 

6 rows selected. 

SQL> select h.hid, h.name 
    2 from hospital h 
    3   inner join work w 
    4     on w.hid = h.hid 
    5   inner join doctor d 
    6     on d.ic = w.ic 
    7 where not exists (select null 
    8      from work w2 
    9      where w2.hid != h.hid 
10      and w2.ic = w.ic) 
11 group by h.hid, h.name 
12 having count(*) > 2; 

     HID NAME 
---------- -------------------- 
     1 General