以下輸出的SQL查詢？

Question

表test與列compname version和表Bugs與bugid compname

數據列test：

A 1.2
B 1.5
C 1.6
B 1.3
C 1.5
A 1.6
B 1.6

數據爲Bugs：

1 A
1 C
2 A
2 B
3 A
3 B
3 C

查詢：

Output the compname where version=1.6 and affected by bugid=1 along with the first(min) version in which the component appeared

輸出：
A 1.2
C 1.5

我使用這個查詢，但可以在此進行得更快：

select compname,min(version) from test where compname IN (select compname from test where version='1.6' and compname IN (select compname from Bugs where bugid=1)) group by compname

Answer 1

聯接速度更快，並且您需要額外的自聯接來獲取最小版本。

SELECT t.compname, min(t2.version) 
FROM test t 
INNER JOIN Bugs b 
    ON t.compname = b.compname 
INNER JOIN test t2 
    ON t.compname = t2.compname 
WHERE bugid = 1 AND t.version='1.6' 
GROUP BY t.compname 

（在我的測試給你列出了相同的結果）

Answer 2

您可以使用INNER JOIN：

SELECT test.compname, min(test.version) 
FROM test INNER JOIN Bugs 
ON test.compname = Bugs.compname 
WHERE test.version = '1.6' AND Bugs.bugid =1 
GROUP BY test.compname