[英]MIN and COUNT Oracle SQL Query
I have tried to this query: What are the hospitals for each country with the lower number of doctors. 我尝试过以下查询:每个国家的医生人数较少的医院是哪些。 (1st column: name of the country; 2nd column: name of the hospital. In case of there is more than hospital with the lower number of doctors it must appear on the result).
(第一列:国家名称;第二列:医院名称。如果有多家医院,而医生人数较少,则必须在结果中显示)。 But the result isn't what I expected and it has a syntax error.
但是结果不是我所期望的,并且有语法错误。
I have these tables: 我有这些表:
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)
);
I tried with this: 我尝试了这个:
SELECT DISTINCT H.country, H.name, MIN(*)
FROM Hospital H
WHERE H.hid IN (
SELECT COUNT(*)
FROM Work W, Doctor D
WHERE W.hid = H.hid AND W.ic = D.ic
GROUP BY H.country
)
GROUP BY H.country
;
Thanks. 谢谢。
SELECT country, name
FROM
(
SELECT hid, country, name, MIN(doctorCount)
FROM
(
SELECT a.hid, a.country, a.name, COUNT(b.hid) doctorCount
FROM Hospital a
LEFT JOIN Work b
ON a.hid = b.hid
GROUP BY a.hid, a.country, a.name
) x
GROUP BY hid, country, name
) y
Try this: 尝试这个:
WITH doctorCount AS
(SELECT H.country country, H.hid hid, COUNT(*) dCount
FROM Work W, Doctor D, Hospital H
WHERE W.ic = D.ic
AND H.hid = W.hid
GROUP BY H.country, H.hid),
minCount AS
(SELECT D.country, MIN (D.dCount) lowCount
FROM doctorCount D
GROUP BY D.country)
SELECT D.country, H.name
FROM doctorCount D, Hospital H, minCount M
WHERE D.hid = H.hid
AND M.country = D.country
AND D.dCount = M.lowCount;
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