How to join 4 tables in mysql PDO?












2















I have 4 tables as below:



1) courses



   | ID - > Primary Key | Name
-------------------------------
| 1 | Course 1
| 2 | Course 2
| 3 | Course 3


2) countries



   | IDPrimary Key | Name
-------------------------------
| 1 | Country 1
| 2 | Country 2
| 3 | Course 3


3) universities



   | ID - > Primary Key | Name           | country_id
---------------------------------------------------
| 1 | University 1 | 1
| 2 | University 2 | 1
| 3 | University 3 | 3


4) university_courses



   | ID - > Primary Key | university_id  | course_id
----------------------------------------------
| 1 | 1 | 2
| 2 | 3 | 2
| 3 | 3 | 3


Now, I need to create one REST API in core PHP for android app in that I will get two parameters country_id and course_id. Both will contain multiple values like country_id = "3,4,5" and course_id = "1,6,8".



I have to response all the related universities according to the country and course.



I have tried below query but i am not getting desired output so please help me if anyone have idea for my problem.



SELECT * 
FROM universities
LEFT JOIN countries ON countries.id = universities.country_id
LEFT JOIN university_courses ON universiity_courses.university_id = universities.id
LEFT JOIN courses ON courses.id = university_courses.course_id
WHERE FIND_IN_SET(universities.country_id, ?)
AND FIND_IN_SET(university_courses.course_id, ?)


If course_id = 1,2 and country_id = 2,3, my desired output should be:



| university_id |
| 3 |









share|improve this question




















  • 1





    You want to use the IN() operator

    – Raymond Nijland
    Jan 1 at 12:42













  • Any way we can use, but need proper output.

    – Jk7
    Jan 1 at 12:44











  • You are using LEFT JOIN which is wrong you need to use a INNER JOIN to get the related relations. Also you JOiN to much tables then you could. You only have to need to JOIN between university_courses and the universities to get the required results

    – Raymond Nijland
    Jan 1 at 12:52













  • Okay, now above issue is partially solved.

    – Jk7
    Jan 1 at 13:12











  • But now i m getting same university twice, if course_id=2,3. So in short Group by is not working.

    – Jk7
    Jan 1 at 13:15
















2















I have 4 tables as below:



1) courses



   | ID - > Primary Key | Name
-------------------------------
| 1 | Course 1
| 2 | Course 2
| 3 | Course 3


2) countries



   | IDPrimary Key | Name
-------------------------------
| 1 | Country 1
| 2 | Country 2
| 3 | Course 3


3) universities



   | ID - > Primary Key | Name           | country_id
---------------------------------------------------
| 1 | University 1 | 1
| 2 | University 2 | 1
| 3 | University 3 | 3


4) university_courses



   | ID - > Primary Key | university_id  | course_id
----------------------------------------------
| 1 | 1 | 2
| 2 | 3 | 2
| 3 | 3 | 3


Now, I need to create one REST API in core PHP for android app in that I will get two parameters country_id and course_id. Both will contain multiple values like country_id = "3,4,5" and course_id = "1,6,8".



I have to response all the related universities according to the country and course.



I have tried below query but i am not getting desired output so please help me if anyone have idea for my problem.



SELECT * 
FROM universities
LEFT JOIN countries ON countries.id = universities.country_id
LEFT JOIN university_courses ON universiity_courses.university_id = universities.id
LEFT JOIN courses ON courses.id = university_courses.course_id
WHERE FIND_IN_SET(universities.country_id, ?)
AND FIND_IN_SET(university_courses.course_id, ?)


If course_id = 1,2 and country_id = 2,3, my desired output should be:



| university_id |
| 3 |









share|improve this question




















  • 1





    You want to use the IN() operator

    – Raymond Nijland
    Jan 1 at 12:42













  • Any way we can use, but need proper output.

    – Jk7
    Jan 1 at 12:44











  • You are using LEFT JOIN which is wrong you need to use a INNER JOIN to get the related relations. Also you JOiN to much tables then you could. You only have to need to JOIN between university_courses and the universities to get the required results

    – Raymond Nijland
    Jan 1 at 12:52













  • Okay, now above issue is partially solved.

    – Jk7
    Jan 1 at 13:12











  • But now i m getting same university twice, if course_id=2,3. So in short Group by is not working.

    – Jk7
    Jan 1 at 13:15














2












2








2








I have 4 tables as below:



1) courses



   | ID - > Primary Key | Name
-------------------------------
| 1 | Course 1
| 2 | Course 2
| 3 | Course 3


2) countries



   | IDPrimary Key | Name
-------------------------------
| 1 | Country 1
| 2 | Country 2
| 3 | Course 3


3) universities



   | ID - > Primary Key | Name           | country_id
---------------------------------------------------
| 1 | University 1 | 1
| 2 | University 2 | 1
| 3 | University 3 | 3


4) university_courses



   | ID - > Primary Key | university_id  | course_id
----------------------------------------------
| 1 | 1 | 2
| 2 | 3 | 2
| 3 | 3 | 3


Now, I need to create one REST API in core PHP for android app in that I will get two parameters country_id and course_id. Both will contain multiple values like country_id = "3,4,5" and course_id = "1,6,8".



I have to response all the related universities according to the country and course.



I have tried below query but i am not getting desired output so please help me if anyone have idea for my problem.



SELECT * 
FROM universities
LEFT JOIN countries ON countries.id = universities.country_id
LEFT JOIN university_courses ON universiity_courses.university_id = universities.id
LEFT JOIN courses ON courses.id = university_courses.course_id
WHERE FIND_IN_SET(universities.country_id, ?)
AND FIND_IN_SET(university_courses.course_id, ?)


If course_id = 1,2 and country_id = 2,3, my desired output should be:



| university_id |
| 3 |









share|improve this question
















I have 4 tables as below:



1) courses



   | ID - > Primary Key | Name
-------------------------------
| 1 | Course 1
| 2 | Course 2
| 3 | Course 3


2) countries



   | IDPrimary Key | Name
-------------------------------
| 1 | Country 1
| 2 | Country 2
| 3 | Course 3


3) universities



   | ID - > Primary Key | Name           | country_id
---------------------------------------------------
| 1 | University 1 | 1
| 2 | University 2 | 1
| 3 | University 3 | 3


4) university_courses



   | ID - > Primary Key | university_id  | course_id
----------------------------------------------
| 1 | 1 | 2
| 2 | 3 | 2
| 3 | 3 | 3


Now, I need to create one REST API in core PHP for android app in that I will get two parameters country_id and course_id. Both will contain multiple values like country_id = "3,4,5" and course_id = "1,6,8".



I have to response all the related universities according to the country and course.



I have tried below query but i am not getting desired output so please help me if anyone have idea for my problem.



SELECT * 
FROM universities
LEFT JOIN countries ON countries.id = universities.country_id
LEFT JOIN university_courses ON universiity_courses.university_id = universities.id
LEFT JOIN courses ON courses.id = university_courses.course_id
WHERE FIND_IN_SET(universities.country_id, ?)
AND FIND_IN_SET(university_courses.course_id, ?)


If course_id = 1,2 and country_id = 2,3, my desired output should be:



| university_id |
| 3 |






php mysql pdo






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Jan 1 at 13:24









RiggsFolly

71.1k1864111




71.1k1864111










asked Jan 1 at 12:38









Jk7Jk7

142




142








  • 1





    You want to use the IN() operator

    – Raymond Nijland
    Jan 1 at 12:42













  • Any way we can use, but need proper output.

    – Jk7
    Jan 1 at 12:44











  • You are using LEFT JOIN which is wrong you need to use a INNER JOIN to get the related relations. Also you JOiN to much tables then you could. You only have to need to JOIN between university_courses and the universities to get the required results

    – Raymond Nijland
    Jan 1 at 12:52













  • Okay, now above issue is partially solved.

    – Jk7
    Jan 1 at 13:12











  • But now i m getting same university twice, if course_id=2,3. So in short Group by is not working.

    – Jk7
    Jan 1 at 13:15














  • 1





    You want to use the IN() operator

    – Raymond Nijland
    Jan 1 at 12:42













  • Any way we can use, but need proper output.

    – Jk7
    Jan 1 at 12:44











  • You are using LEFT JOIN which is wrong you need to use a INNER JOIN to get the related relations. Also you JOiN to much tables then you could. You only have to need to JOIN between university_courses and the universities to get the required results

    – Raymond Nijland
    Jan 1 at 12:52













  • Okay, now above issue is partially solved.

    – Jk7
    Jan 1 at 13:12











  • But now i m getting same university twice, if course_id=2,3. So in short Group by is not working.

    – Jk7
    Jan 1 at 13:15








1




1





You want to use the IN() operator

– Raymond Nijland
Jan 1 at 12:42







You want to use the IN() operator

– Raymond Nijland
Jan 1 at 12:42















Any way we can use, but need proper output.

– Jk7
Jan 1 at 12:44





Any way we can use, but need proper output.

– Jk7
Jan 1 at 12:44













You are using LEFT JOIN which is wrong you need to use a INNER JOIN to get the related relations. Also you JOiN to much tables then you could. You only have to need to JOIN between university_courses and the universities to get the required results

– Raymond Nijland
Jan 1 at 12:52







You are using LEFT JOIN which is wrong you need to use a INNER JOIN to get the related relations. Also you JOiN to much tables then you could. You only have to need to JOIN between university_courses and the universities to get the required results

– Raymond Nijland
Jan 1 at 12:52















Okay, now above issue is partially solved.

– Jk7
Jan 1 at 13:12





Okay, now above issue is partially solved.

– Jk7
Jan 1 at 13:12













But now i m getting same university twice, if course_id=2,3. So in short Group by is not working.

– Jk7
Jan 1 at 13:15





But now i m getting same university twice, if course_id=2,3. So in short Group by is not working.

– Jk7
Jan 1 at 13:15












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