我正在看微软认证考试中的一些试题。我遇到这个问题,我回答错了,不明白为什么.
问题
2. An employee at a reputable ISP tells Maxim that they use Windows Server and that he needs
to understand the basics of Internet Information Services (IIS). Which of the following is NOT
a role of IIS?
a. to deliver HTML documents to web browsers
b
我有以下两种表格结构:
试题表
QuestionID | Response
1 Yes
2 No
1 No
问题查找表
QuestionID | Lookup
1 No
2 No
3 No
当查找和响应相等时,我试图得到一个之和。例如,QuestionID 1的查找值为"No“。在试题表中,有两个问题In的值为1。其中一个响应的值为No,因此我会将返回值增加1,并将最终结果按QuestionID分组。
我正在从事一个具有大型Question银行的项目,对于系统中的Tests added,将根据以下查询在运行时动态获取20个问题:
SELECT Question.* from Question JOIN Test
ON Question.Subject_ID = Test.Subject_ID
AND Question.Question_Level = Test.Test_Level
ORDER BY RAND()
LIMIT 20;
但是,众所周知,RAND()函数-- MySQL杀死了您的服务器--我一直在寻找更好的解决方案。
的 EXPLAIN [above query]结果
+
我有两张桌子(试题表和答题表)。
试题表
id question
1 what is your name?
2 how old are you?
答案表
id answer questionid
1 john 1
2 smith 1
3 waiyan 1
4 20 2
5 21 2
6 22 2
当我选择记录时,结果如下。
SELECT * FROM question INNER JOIN answer on questionid= question.id
what is your name?
john
w