CODEWITHSUNDEEP
mysqljoin
Matthew
Matthew

Reputation: 3946

SQL syntax issue with INNER JOIN

I have three tables in MySql. Table 1 has the following fields

Table1: 

EventType
-etid
-description

Table 2:

EventAsks
-etid
-qid

Table 3:

Questions
-qid
-textofquestion

If I have a specific etid and I want to find all the questions that the event asks for. So given the following tables...

EventType
etid     description
1        hiking
2        biking


EventAsks
etid      qid
1         1
1         3
2         2
2         3

Questions
qid   textofquestion
1     Is it fun?
2     Is it lots of exercise
3     Is it expensive

So the result of a given etid say etid=1, I would like the questions associated with etid=1 returned...

Result
Is it fun?
Is it expensive?

I am sure this had to do with a join, but I don't know exactly how to do it? Any suggestions?

Upvotes: 0

Views: 43

Answers (2)

Madbreaks
Madbreaks

Reputation: 19539

Classic n-to-n relationship:

SELECT Questions.textofquestion FROM EventType
LEFT JOIN EventAsks ON EventAsks.etid = EventType.etid
LEFT JOIN Questions ON Questions.quid = EventAsks.qid
WHERE EventType.etid = 1;

Upvotes: 3

RMalke
RMalke

Reputation: 4094

You can do:

SELECT Questions.textofquestion
FROM EventType
   INNER JOIN EventAsks 
        ON EventType.etid = EventAsks.etid
   INNER JOIN Questions 
        ON EventAsks.qid = Questions.qid
WHERE EventType.etid = 1

Since you already have the etid=1 yuou can simplify as:

SELECT Questions.textofquestion
FROM EventAsks 
   INNER JOIN Questions 
        ON EventAsks.qid = Questions.qid
WHERE EventAsks.etid = 1

Upvotes: 2

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