Please be assured that I searched a lot on SE for an answer similar to mine but didn't get any good result and here I am asking for some help.
I have 3 tables as follows:
Table Professors:
+---------+--------+
| idProf | name |
+---------+--------+
| 1 | Ben |
| 2 | John |
| 3 | Bob |
+---------+--------+
Table Classes:
+---------+--------+------------+
| idClass | name | profRefId |
+---------+--------+------------+
| 1 | French | 1 |
| 2 | English| 1 |
| 3 | German | 3 |
| 4 | Science| 2 |
+---------+--------+------------+
Table Lessons:
+----------+----------+--------------+
| idLesson | name | classRefId |
+----------+----------+--------------+
| 1 | Lesson1 | 1 |
| 2 | Lesson2 | 1 |
| 3 | Lesson3 | 2 |
| 4 | Lesson4 | 4 |
| 5 | Lesson5 | 4 |
| 6 | Lesson6 | 3 |
+----------+----------+--------------+
Now, what I was struggling to achieve is:
I pass idProf as a URL parameter ($_GET['idProf'])
And I would like the right SQL statement based on that param to list all the classes for that professor and inside each class list its lessons.
Something that will look like this on a webpage:
Something like this?
SELECT a.name ProfessorName, b.name ClassName, c.name LessonName
FROM Professors a
INNER JOIN Classes b
ON a.idProf=b.profRefID
INNER JOIN Lessons c
ON b.idClass=c.classRefID
Related
I have this tables People, Ticket, and Report.
+----------+-------+-----+
| idPeople | Name | Age |
+----------+-------+-----+
| 1 | Name1 | 21 |
| 2 | Name2 | 37 |
| 3 | Name3 | 28 |
+----------+-------+-----+
I would like to replace the ForeingKey idPeople with columns Name and Age from People table.
+----------+------------+------------+----------+
| idTicket | ticketCol2 | ticketCol3 | idPeople |
+----------+------------+------------+----------+
| 5 | True | 01/06/99 | 1 |
| 6 | False | 01/06/99 | 2 |
| 7 | True | 01/06/99 | 4 |
+----------+------------+------------+----------+
In the Report table replace the Foreing Key idTicket with ticketCol2, Name, Age from the previous table Ticket with replaced columns (idPeople by Name, Age).
+----------+----------+------------+------------+
| idReport | idTicket | ReportCol3 | ReportCol4 |
+----------+----------+------------+------------+
| 1 | 5 | 01/06/99 | blabla |
| 2 | 7 | 01/06/99 | asdfdd |
| 2 | 6 | 01/06/99 | fooboo |
+----------+----------+------------+------------+
And I the result should be like this table and must be done in one query.
+----------+------------+------------+------------+------------+------+-----+
| idReport | ticketCol2 | ticketCol3 | ReportCol3 | ReportCol4 | Name | Age |
+----------+------------+------------+------------+------------+------+-----+
| 1 | 01/06/99 | abcd | blabla | 123456 | Name | 20 |
| 2 | 01/06/99 | bcda | asdfdd | 321456 | Name | 23 |
| 3 | 01/06/99 | asdf | fooboo | 123456 | Name | 28 |
+----------+------------+------------+------------+------------+------+-----+
I Have tried replacing the foreingkeys with LEFT JOIN and bringing some columns Name and Age to the Ticket table but now the last part where I should replace idTicket with Columns from Ticket is not working.
I have read about the nested JOINs but I cannot understand it very well, I would really appreciate some idea of how I can do it or what should I investigate. Are nested Joins the right way?
The query that I've tried to accomplish the Table Ticket.
SELECT Ticket.ticketCol2, Ticket.ticketCol3, p.Name 'Name', p.Age 'Age'
from Ticket
left join people p on (Ticket.idPeople=p.idPeople);
Try something like this:
SELECT Report.idReport,
Ticket.ticketCol2,
Ticket.ticketCol3,
Report.ReportCol3,
Report.ReportCol4,
People.Name,
People.Age
FROM People
LEFT JOIN Ticket ON Ticket.idPeople = People.idPeople
LEFT JOIN Report ON Report.idTicket = Ticket.idTicket
Like #RiggsFolly said, the Ticket.idPeople won´t match to the People.idPeople, so this will not match any rows.
this is my first time posting here. I don't seem to find the answer to my problem.
So... I'm arranging a DB for a school project, a cookbook that only shows recipes that can be made with existing elements from the "shelf".
These ingredients have to have an exact ingredients match.
user:
+---------------+------+----------+----------+
| email | name | lastname | password |
+---------------+------+----------+----------+
| pal#mail.com | John | Potato | password |
| they#mail.com | Mary | Carrot | password |
+---------------+------+----------+----------+
shelf:
+---------+------------+---------------+
| shelfID | ingredient | user |
+---------+------------+---------------+
| 1 | 1 | pal#mail.com |
| 2 | 2 | pal#mail.com |
| 3 | 3 | pal#mail.com |
| 4 | 4 | pal#mail.com |
| 5 | 10 | they#mail.com |
| 6 | 12 | they#mail.com |
+---------+------------+---------------+
This is my recipe_ingredient relationship table
recipe_ingredient:
+--------+------------+
| recipe | ingredient |
+--------+------------+
| 1 | 1 |
| 1 | 2 |
| 1 | 4 |
| 1 | 10 |
| 2 | 1 |
| 2 | 2 |
| 2 | 3 |
| 2 | 4 |
| 3 | 2 |
| 3 | 3 |
| 3 | 15 |
+--------+------------+
I've tried this query:
SELECT
rec_ing.recipe, shf.ingredient, shf.user
FROM
recipes_ingredients AS rec_ing
INNER JOIN
shelf AS shf ON rec_ing.ingredient = shf.ingredient
INNER JOIN
users AS usr ON shf.user = usr.email
WHERE
usr.email = 'pal#mail.com'
that returns this table:
+--------+------------+--------------+
| recipe | ingredient | user |
+--------+------------+--------------+
| 1 | 1 | pal#mail.com |
| 1 | 2 | pal#mail.com |
| 1 | 4 | pal#mail.com |
| 2 | 1 | pal#mail.com |
| 2 | 2 | pal#mail.com |
| 2 | 3 | pal#mail.com |
| 2 | 4 | pal#mail.com |
| 3 | 2 | pal#mail.com |
| 3 | 3 | pal#mail.com |
+--------+------------+--------------+
Although it's true that the Recipe 1 contains ingredients from my shelf, it's also missing Ingredient 10
+--------+------------+
| recipe | ingredient |
+--------+------------+
| 1 | 1 |
| 1 | 2 |
| 1 | 4 |
| 1 | 10 |
| ... | ... |
+--------+------------+
I'm trying to only get this kind of result set.
+--------+------------+
| recipe | ingredient |
+--------+------------+
| 2 | 1 |
| 2 | 2 |
| 2 | 3 |
| 2 | 4 |
+--------+------------+
Because Recipe 2 contains all elements from my shelf
I have been going around all day with this problem ... What could be missing?
This is a bit tricky, because you need to aggregate your current query by recipe, but you also need the original query to get back the full records. Sadly, MySQL does not support common table exprrssions or other features which could give us a less verbose query.
SELECT
rec_ing.recipe,
shf.ingredient,
shf.user
FROM recipes_ingredients AS rec_ing
INNER JOIN shelf AS shf
ON rec_ing.ingredient = shf.ingredient
INNER JOIN users AS usr
ON shf.user = usr.email
INNER JOIN
(
SELECT rec_ing.recipe
FROM recipes_ingredients AS rec_ing
INNER JOIN shelf AS shf
ON rec_ing.ingredient = shf.ingredient
LEFT JOIN users AS usr
ON shf.user = usr.email
WHERE
usr.email = 'pal#mail.com'
GROUP BY rec_ing.recipe
HAVING COUNT(usr.email) = COUNT(*)
) t
ON rec_ing.recipe = t.recipe
WHERE
usr.email = 'pal#mail.com'
The basic strategy here is to just do one additional join to a subquery which identifies all recipes where every ingredient belongs to a given user. The critical part is the following:
HAVING COUNT(usr.email) = COUNT(*)
This checks that the total number of rows for a given recipe matches the number of rows which have been assigned to a given user.
I have the next table setup, two tables related by an intermediate table, like this:
Client
| client_id | ...|field_X |
| 1 | ...|value1 |
| 2 | ...|value2 |
| 3 | ...|value3 |
Project
| project_id | ...|field_X |
| 1 | ...| |
| 2 | ...| |
| 3 | ...| |
| 4 | ...| |
| 5 | ...| |
| 6 | ...| |
| 7 | ...| |
client_project
| client_id | project_id|
| 1 | 2 |
| 1 | 3 |
| 2 | 4 |
| 2 | 5 |
| 3 | 6 |
| 3 | 7 |
The field_x in the table project is new and i have to fill it with the data from table client to get approximately something like this:
Project
| project_id | ...|field_X |
| 1 | ...| |
| 2 | ...|value1 |
| 3 | ...|value1 |
| 4 | ...|value2 |
| 5 | ...|value2 |
| 6 | ...|value3 |
| 7 | ...|value3 |
i dont know hot to deal with the intermediate table. i have tried this code but it doesnt work.
INSERT INTO project
(field_x)
(select field_x
from
client_project
inner join
client
where client_project.client_id = client.client_id
);
I have the idea of what i have to do but i am not able to translate it into a sql command because of the intermeditate table.Could someone explain how to deal with it?
Thanks in advance.
I assume you already have all entries in the project table but they're missing the Field_X property? So what you need is an update, not an insert
UPDATE project p, client c, project_client pc SET p.Field_X=c.Field_X WHERE p.ID=pc.ProjectID AND c.ID=pc.ClientID
However, be advised that having the same data in two places is not a good practise; if possible always put one fact in only one place.
I'm relatively new to MySQL and have come across a problem to which I cannot seem to find a solution. I have searched but could not find an answer. I'm open to the possibility that I'm not asking the question correctly. Here goes:
I'm trying to use the name of a given column and the values within that column from one table to pull values from another table. The first table contains 3 columns with the response codified. The second table contains the definitions for each code for each item. The same number code is associated with different meanings depending on the item. For example:
table1 (this table cannot change):
--------------------------------------------------------------
|result_id | f_initial | l_name | item_A | item_B | item_C |
--------------------------------------------------------------
| 1 | j | doe | 1 | 3 | 2 |
| 2 | k | smith | 3 | 1 | 2 |
| 3 | l | williams | 2 | 2 | 1 |
--------------------------------------------------------------
table2 (this table can be modified, split, or whatever needs to be done):
-------------------------------------------
|item_id | item_name | score | definition |
-------------------------------------------
| 1 | item_A | 1 | agree |
| 2 | item_A | 2 | neutral |
| 3 | item_A | 3 | disagree |
| 4 | item_B | 1 | likely |
| 5 | item_B | 2 | not likely |
| 6 | item_B | 3 | no reply |
| 7 | item_C | 1 | yes |
| 8 | item_C | 2 | no |
-------------------------------------------
My goal is for the query to output the following:
--------------------------------------------------------------------
|result_id | f_initial | l_name | item_A | item_B | item_C |
--------------------------------------------------------------------
| 1 | j | doe | agree | no reply | no |
| 2 | k | smith | disagree | likely | no |
| 3 | l | williams | neutral | not likely | yes |
--------------------------------------------------------------------
Any assistance or guidance is greatly appreciated. Thank you in advance.
You must join the two tables on the item_A/B/C and score columns
select t1.result_id, t1.f_initial, t1.l_name,
t2a.definition as item_a,
t2b.definition as item_b,
t2c.definition as item_c
from table1 t1
join table2 t2a on t2a.score = t1.item_a
join table2 t2b on t2b.score = t1.item_b
join table2 t2c on t2c.score = t1.item_c
where t2a.item_name = 'item_A'
and t2b.item_name = 'item_B'
and t2c.item_name = 'item_C'
I have two tables like below,
mysql> select * from Books ;
+----+------+------------+----------+----------+
| id | name | author_name| category | category2|
+----+------+------------+----------+----------+
| 1 | 1 | Steve | CT001 | CT003 |
| 2 | 2 | John | CT002 | CT002 |
| 3 | 3 | Larry | CT003 | CT002 |
| 4 | 3 | Michael | CT004 | CT004 |
| 5 | NULL | Steven | CT005 | CT005 |
+----+------+------------+----------+----------+
mysql> select * from Codemst ;
+----+------+------------+
| id | code | name |
+----+------+------------+
| 1 | CT001| fiction |
| 2 | CT002| category1 |
| 3 | CT003| etc |
| 4 | CT004| etc2 |
| 5 | CT005| etc3 |
+----+------+------------+
I want to get human readable category name when I query like "select * from Books;"
If there was only one category in the Books table, I think I can use "Join" but, in this case what can I do?
select * from Books b
Inner Join Codemst c1 on b.category = c1.code
inner join codemst c2 on b.category2 = c2.code;
c1.name will hold the readable category, and c2.name the readable category2