Try to join more than one table - mysql

Tables And what i need
I'm trying to Create a view with 5 tables for a school project. The statement so far goes like this:
CREATE view lager AS
Select produkt.produktNumber,
(SELECT buyphone.lagerNummer FROM bluecity.buyphone) AS 'Lagernummer',
produkt.produktBrand,
produkt.produktModel,
sizeMemory.memoryInformation,
(SELECT buyphone.colorValue FROM bluecity.buyphone) AS 'Farve',
(SELECT buyphone.conditionValue FROM bluecity.buyphone) AS 'Stand'
FROM bluecity.produkt
JOIN bluecity.sizememory ON bluecity.produkt.memorySize = bluecity.sizememory.memorySize
JOIN bluecity.color ON buyphone.colorValue = bluecity.color.colorInformation
JOIN bluecity.conditions ON buyphone.conditionValue = bluecity.conditions.conditionInformation
But i can't seem to get the joins right. The main table bluecity.produkt needs to join some of it's values with other table. The first join with Memory size works, but that is it. The main table is supposed to hold an Integer Value which draws meaning from the joined table if that makes sense.
Help is much appriciated, if you can explain why and how it would be even better so i can try to understand.
Added create stmt
CREATE DATABASE bluecity;
CREATE TABLE bluecity.Member
(memberNumber INTEGER(5) NOT NULL,
firstName VARCHAR(50) NOT NULL,
lastName VARCHAR(25) NOT NULL,
address VARCHAR(40) NOT NULL,
zipNumber INTEGER(4) NOT NULL,
phoneNumber INTEGER(8) NOT NULL,
email VARCHAR(35) NOT NULL,
statusValue INTEGER(1) NOT NULL,
FOREIGN KEY (zipNumber) REFERENCES bluecity.zipCode(zipNumber),
FOREIGN KEY (statusValue) REFERENCES bluecity.ID(statusValue),
PRIMARY KEY (memberNumber));
CREATE TABLE bluecity.ID
(statusValue INTEGER(1) NOT NULL,
information VARCHAR(19) NOT NULL,
PRIMARY KEY (statusValue))
CREATE TABLE bluecity.zipCode
(zipNumber INTEGER(4) NOT NULL,
city VARCHAR(32) NOT NULL,
PRIMARY KEY (zipNumber));
CREATE TABLE bluecity.Produkt
(produktNumber INTEGER(5) NOT NULL,
produktType VARCHAR(30) NOT NULL,
produktBrand VARCHAR(30) NOT NULL,
produktModel VARCHAR(30) NOT NULL,
memorySize INTEGER(2) NOT NULL,
FOREIGN KEY (memorySize) REFERENCES bluecity.sizeMemory(memorySize),
PRIMARY KEY (produktNumber));
CREATE TABLE bluecity.Conditions
(conditionValue INTEGER(1) NOT NULL,
conditionInformation VARCHAR(13) NOT NULL,
PRIMARY KEY (conditionValue));
CREATE TABLE bluecity.sizeMemory
(memorySize INTEGER(1) NOT NULL,
memoryInformation VARCHAR(5) NOT NULL,
PRIMARY KEY (memorySize));
CREATE TABLE bluecity.Color
(colorValue INTEGER(2) NOT NULL,
colorInformation VARCHAR(20) NOT NULL,
PRIMARY KEY (colorValue));
CREATE TABLE bluecity.Prices
(conditionValue INTEGER(1) NOT NULL,
produktNumber INTEGER(5) NOT NULL,
price INTEGER(6) NOT NULL,
FOREIGN KEY (conditionValue) REFERENCES bluecity.Conditions(conditionValue),
FOREIGN KEY (produktNumber) REFERENCES bluecity.Produkt(produktNumber),
PRIMARY KEY (conditionValue, produktNumber));
CREATE TABLE bluecity.buyPhone
(IMEI Integer(15) NOT NULL,
lagerNummer INTEGER(7) NOT NULL,
produktNumber INTEGER(5) NOT NULL,
colorValue INTEGER(2) NOT NULL,
conditionValue INTEGER(1) NOT NULL,
FOREIGN KEY (produktNumber) REFERENCES bluecity.Produkt(produktNumber),
FOREIGN KEY (colorValue) REFERENCES bluecity.Color(colorValue),
FOREIGN KEY (conditionValue) REFERENCES bluecity.Conditions(conditionValue), PRIMARY KEY (IMEI));


You should also make a join on the bluecity.buyphone instead of having it as subqueries in your select, as it is related to your produkt table.
Something like this:
Select produkt.produktNumber,
buyphone.lagerNummer AS 'Lagernummer',
produkt.produktBrand,
produkt.produktModel,
sizeMemory.memoryInformation,
buyphone.colorValue AS 'Farve',
buyphone.conditionValue AS 'Stand'
FROM produkt
JOIN buyphone ON buyphone.produktNumber = produkt.produktNumber
JOIN sizememory ON produkt.memorySize = sizememory.memorySize
JOIN color ON buyphone.colorValue = color.colorInformation
JOIN conditions ON buyphone.conditionValue = conditions.conditionInformation


Select DISTINCT produkt.produktNumber AS 'Produkt #',
buyphone.lagerNummer AS 'Lager #',
produkt.produktBrand AS 'Mærke',
produkt.produktModel AS 'Model',
sizeMemory.memoryInformation 'Hukommelse',
color.colorInformation AS 'Farve',
conditions.conditionInformation AS 'Stand',
prices.price AS 'Pris'
FROM bluecity.buyphone
JOIN bluecity.produkt ON bluecity.buyphone.produktNumber = bluecity.produkt.produktNumber
JOIN bluecity.sizememory ON bluecity.produkt.memorySize = bluecity.sizememory.memorySize
JOIN bluecity.color ON bluecity.buyphone.colorValue = bluecity.color.colorValue
JOIN bluecity.conditions ON bluecity.buyphone.conditionValue = bluecity.conditions.conditionValue
JOIN bluecity.prices ON bluecity.produkt.produktNumber = bluecity.prices.produktNumber
JOIN bluecity.prices p1 ON bluecity.buyphone.conditionValue = bluecity.prices.conditionValue
I got it working like this, thx guys.
Edit: there still was some flaws which i think is fixed now.

Related

Creating a MySQL trigger to set a boolean value to true if a collection of booleans are true

I am creating an inventory management app in node.js that uses MySQL as a database. I have a weak entity “rental_item” that holds the items in a particualr rental. The issue is that the rental may not come back all at once so I need a way of marking the “rental_returned” boolean in the rental table true only when all of the “item_returned” entires are true.
Here is my table structure:
CREATE TABLE `rental` (
`rental_id` int NOT NULL AUTO_INCREMENT,
`renter_id` int NOT NULL,
`date_in` date NOT NULL,
`date_out` date NOT NULL,
`sig_path` varchar(50) NOT NULL,
`doc_path` varchar(50) NOT NULL,
`col_name` varchar(50) NOT NULL,
`col_path` varchar(50) NOT NULL,
`cost` decimal(15,2) NOT NULL,
`rental_returned` tinyint(1) NOT NULL DEFAULT '0',
PRIMARY KEY (`rental_id`),
UNIQUE KEY `doc_path` (`doc_path`),
UNIQUE KEY `col_path` (`col_path`),
UNIQUE KEY `sig_path` (`sig_path`),
KEY `renter_key` (`renter_id`),
CONSTRAINT `renter_key` FOREIGN KEY (`renter_id`) REFERENCES `renter` (`renter_id`)
)
CREATE TABLE `rental_item` (
`rental_id` int NOT NULL,
`i_ID` varchar(20) NOT NULL,
`item_returned` tinyint(1) NOT NULL DEFAULT '0',
KEY `rental_key` (`rental_id`),
KEY `rental_item_key` (`i_ID`),
CONSTRAINT `rental_item_key` FOREIGN KEY (`i_ID`) REFERENCES `item` (`i_ID`),
CONSTRAINT `rental_key` FOREIGN KEY (`rental_id`) REFERENCES `rental` (`rental_id`) ON DELETE CASCADE
)
I am currently doing this through the mysql2 node.js module and just checking for all the values of a given rental_id. I then found out about triggers and thought this way could be better. I fiddled round with things like this Trigger with table join, but couldn’t wrap my head around how to get the rental_id of the entry that was updated from rental_item, then check that all entires in rental_item with that id have item_returned = 1, and finally update the rental table to show that all the items/the complete rental has been returned.
I understand that this sould be an update after trigger on rental_item but dont know how to handle the conditionals or loops needed.

Use NEW.rental_id to get the ID of the row that was updated.
CREATE TRIGGER rental_returned AFTER UPDATE ON rental_item
FOR EACH ROW
UPDATE rental
SET rental_returned = (
NOT EXISTS (
SELECT *
FROM rental_item
WHERE rental_id = NEW.rental_id
AND item_returned = 0))
WHERE rental_id = NEW.rental_id

How to write mysql query, where i need to put order by before group by

//I know that there are questions like this before, but I can't get this to work
So, I have 3 tables, seats(id, type_id, hall_id), seat_types(id(PK), type_name) and taken_seats(screening_id(PK), seat_id(PK), type_id).
I need to write a query where I pass a screening ID and hall ID, and get back seat_id,type_name, and isTaken (if seat is taken or not).
The problem I have is that I have a query that return a duplicate if I do ORDER BY, but if I do GROUP BY I don't get correct data back because I didn't ordered it.
My query:
USE cinema_app;
SELECT
seats.id,
seat_types.type_name,
taken_seats.screening_id,
CASE
WHEN taken_seats.screening_id = 3 THEN 'ATaken'
ELSE 'Not taken'
END AS isTaken
FROM seats
JOIN seat_types ON seats.type_id = seat_types.id
LEFT JOIN taken_seats ON taken_seats.seat_id = seats.id
WHERE seats.hall_id = 2
ORDER BY seats.id, isTaken;
Table I'm getting back:
https://imgur.com/tnmCIHi
(id 181)
Database create script:
DROP DATABASE cinema_app;
CREATE DATABASE cinema_app CHARACTER SET UTF8MB4;
USE cinema_app;
CREATE TABLE roles (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
role_name VARCHAR(20) NOT NULL
);
CREATE TABLE ranks (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
rank_name VARCHAR(20) NOT NULL
);
CREATE TABLE users (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
first_name VARCHAR(100) NOT NULL,
last_name VARCHAR(100) NOT NULL,
birthdate DATE NOT NULL,
email VARCHAR(100) NOT NULL,
pass VARCHAR(20) NOT NULL,
phone_number VARCHAR(20) NOT NULL,
created_at TIMESTAMP NOT NULL DEFAULT NOW(),
role_id INT NOT NULL,
FOREIGN KEY (role_id) REFERENCES roles(id)
);
CREATE TABLE user_ranks (
user_id INT NOT NULL,
rank_id INT NOT NULL,
PRIMARY KEY (user_id, rank_id),
FOREIGN KEY (user_id) REFERENCES users(id),
FOREIGN KEY (rank_id) REFERENCES ranks(id)
);
CREATE TABLE movies (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
TMDB_id INT NOT NULL
);
CREATE TABLE spectacles (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
title VARCHAR(255) NOT NULL,
poster_img MEDIUMBLOB,
time_length TIME NOT NULL
);
CREATE TABLE hall_types (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
type_name VARCHAR(10) NOT NULL
);
CREATE TABLE halls (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
type_id INT NOT NULL,
FOREIGN KEY (type_id) REFERENCES hall_types(id)
);
CREATE TABLE screening_types (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
type_name VARCHAR(20) NOT NULL
);
CREATE TABLE screening_visions (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
vision_name VARCHAR(10) NOT NULL
);
CREATE TABLE screenings (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
starting_date_time TIMESTAMP NOT NULL,
ending_date_time TIMESTAMP NOT NULL,
first_pause BOOL NOT NULL,
second_pause BOOL NOT NULL,
ticket_price DECIMAL(4,2) NOT NULL,
private_screening BOOL NOT NULL,
hall_id INT NOT NULL,
movie_id INT,
spectacle_id INT,
type_id INT NOT NULL,
vision_id INT NOT NULL,
FOREIGN KEY (hall_id) REFERENCES halls(id),
FOREIGN KEY (movie_id) REFERENCES movies(id),
FOREIGN KEY (spectacle_id) REFERENCES spectacles(id),
FOREIGN KEY (type_id) REFERENCES screening_types(id),
FOREIGN KEY (vision_id) REFERENCES screening_visions(id)
);
CREATE TABLE private_screening_reqs (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
starting_date_time TIMESTAMP NOT NULL,
ending_date_time TIMESTAMP NOT NULL,
first_pause BOOL NOT NULL,
second_pause BOOL NOT NULL,
people_number INT NOT NULL,
price DECIMAL(5,2) NOT NULL,
TMDB_id INT NOT NULL,
hall_id INT NOT NULL,
user_id INT NOT NULL,
FOREIGN KEY (hall_id) REFERENCES halls(id),
FOREIGN KEY (user_id) REFERENCES users(id)
);
CREATE TABLE seat_types (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
type_name VARCHAR(15) NOT NULL
);
CREATE TABLE seats (
id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
type_id INT NOT NULL,
hall_id INT NOT NULL,
FOREIGN KEY (hall_id) REFERENCES halls(id),
FOREIGN KEY (type_id) REFERENCES seat_types(id)
);
CREATE TABLE taken_seats (
screening_id INT NOT NULL,
seat_id INT NOT NULL,
user_id INT,
PRIMARY KEY (screening_id, seat_id),
FOREIGN KEY (screening_id) REFERENCES screenings(id),
FOREIGN KEY (seat_id) REFERENCES seats(id),
FOREIGN KEY (user_id) REFERENCES users(id)
);
SAMPLE data (CSV):
hall_types:
id,type_name
1,2D
2,"2D Extreme"
3,3D
4,"3D Extreme"
5,"Real 3D"
6,4DX
halls:
id,type_id
1,1
2,2
3,2
4,5
5,6
screening_types:
id,type_name
1,Normal
2,Premiere
3,Preprempere
4,"Late night"
5,Kids
screening_visions:
id,vision_name
1,2D
2,"2D Extreme"
3,3D
4,"3D Extreme"
5,"Real 3D"
6,4DX
movies:
id,TMDB_id
1,255
2,314
3,142
screenings:
id,starting_date_time,ending_date_time,first_pause,second_pause,ticket_price,private_screening,hall_id,movie_id,spectacle_id,type_id,vision_id
1,"2022-03-24 19:00:00","2022-03-24 20:00:00",0,0,8.00,0,2,1,NULL,1,2
2,"2022-03-24 21:30:00","2022-03-24 22:45:00",1,0,7.50,0,1,1,NULL,1,1
3,"2022-03-24 20:10:00","2022-03-24 22:10:00",1,0,9.00,0,2,2,NULL,2,2
4,"2022-03-25 20:10:00","2022-03-25 22:10:00",0,0,7.00,0,3,3,NULL,2,3
seat_types:
id,type_name
1,Normal
2,VIP
3,LoveBox
seats:
id,type_id,hall_id
1,1,1
2,1,1
3,1,1
4,1,1
5,1,1
6,1,1
7,1,1
8,1,1
9,1,1
10,1,1
11,1,1
12,1,1
13,1,1
14,1,1
15,1,1
16,1,1
17,1,1
18,1,1
19,1,1
20,1,1
21,1,1
22,1,1
23,1,1
24,1,1
25,1,1
26,1,1
27,1,1
28,1,1
29,1,1
30,1,1
31,1,1
32,1,1
33,1,1
34,1,1
35,1,1
36,1,1
37,1,1
38,1,1
39,1,1
40,1,1
41,1,1
42,1,1
43,1,1
44,1,1
45,1,1
46,1,1
47,1,1
48,1,1
49,1,1
50,1,1
51,1,1
52,1,1
53,1,1
54,1,1
55,1,1
56,1,1
57,1,1
58,1,1
59,1,1
60,1,1
61,1,1
62,1,1
63,1,1
64,1,1
65,1,1
66,1,1
67,1,1
68,1,1
69,1,1
70,1,1
71,1,1
72,1,1
73,1,1
74,1,1
75,1,1
76,1,1
77,1,1
78,1,1
79,1,1
80,1,1
81,1,1
82,1,1
83,1,1
84,1,1
85,1,1
86,1,1
87,1,1
88,1,1
89,1,1
90,1,1
91,1,1
92,1,1
93,1,1
94,1,1
95,1,1
96,1,1
97,1,1
98,1,1
99,1,1
100,1,1
101,1,1
102,1,1
103,1,1
104,1,1
105,1,1
106,1,1
107,1,1
108,1,1
109,1,1
110,1,1
111,1,1
112,1,1
113,1,1
114,1,1
115,1,1
116,1,1
117,1,1
118,1,1
119,1,1
120,2,1
121,2,1
122,2,1
123,2,1
124,2,1
125,2,1
126,2,1
127,2,1
128,2,1
129,2,1
130,2,1
131,2,1
132,2,1
133,2,1
134,2,1
135,2,1
136,2,1
137,3,1
138,3,1
139,3,1
140,3,1
141,3,1
142,3,1
143,3,1
144,3,1
145,3,1
146,1,2
147,1,2
148,1,2
149,1,2
150,1,2
151,1,2
152,1,2
153,1,2
154,1,2
155,1,2
156,1,2
157,1,2
158,1,2
159,1,2
160,1,2
161,1,2
162,1,2
163,1,2
164,1,2
165,1,2
166,1,2
167,1,2
168,1,2
169,1,2
170,1,2
171,1,2
172,1,2
173,1,2
174,1,2
175,1,2
176,1,2
177,1,2
178,1,2
179,1,2
180,1,2
181,1,2
182,1,2
183,1,2
184,1,2
185,1,2
186,1,2
187,1,2
188,1,2
189,1,2
190,1,2
191,1,2
192,1,2
193,1,2
194,1,2
195,1,2
196,1,2
197,1,2
198,1,2
199,1,2
200,1,2
201,1,2
202,1,2
203,1,2
204,1,2
205,1,2
206,1,2
207,1,2
208,1,2
209,1,2
210,1,2
211,1,2
212,1,2
213,1,2
214,1,2
215,1,2
216,1,2
217,1,2
218,1,2
219,1,2
220,1,2
221,1,2
222,1,2
223,1,2
224,1,2
225,1,2
226,1,2
227,1,2
228,1,2
229,1,2
230,1,2
231,1,2
232,1,2
233,1,2
234,1,2
235,1,2
236,1,2
237,1,2
238,1,2
239,1,2
240,1,2
241,1,2
242,1,2
243,1,2
244,1,2
245,1,2
246,1,2
247,1,2
248,1,2
249,1,2
250,1,2
251,1,2
252,1,2
253,1,2
254,1,2
255,1,2
256,1,2
257,1,2
258,1,2
259,1,2
260,1,2
261,1,2
262,1,2
263,1,2
264,1,2
265,1,2
266,1,2
267,1,2
268,1,2
269,1,2
270,1,2
271,1,2
272,1,2
273,1,2
274,1,2
275,1,2
276,1,2
277,1,2
278,1,2
279,1,2
280,1,2
281,1,2
282,1,2
283,1,2
284,1,2
285,1,2
286,1,2
287,1,2
288,1,2
289,1,2
290,1,2
291,1,2
292,1,2
293,1,2
294,1,2
295,1,2
296,1,2
297,1,2
298,1,2
299,1,2
300,1,2
301,1,2
302,1,2
303,1,2
304,1,2
305,1,2
306,1,2
307,1,2
308,1,2
309,1,2
310,1,2
311,1,2
312,1,2
313,1,2
314,1,2
315,1,2
316,1,2
317,1,2
318,1,2
319,1,2
320,1,2
321,1,2
322,1,2
323,1,2
324,1,2
325,1,2
326,1,2
327,1,2
328,1,2
329,1,2
330,1,2
331,1,2
332,1,2
333,1,2
334,1,2
335,1,2
336,1,2
337,1,2
338,1,2
339,1,2
340,1,2
341,1,2
342,1,2
343,1,2
344,1,2
345,1,2
346,2,2
347,2,2
348,2,2
349,2,2
350,2,2
351,2,2
352,2,2
353,2,2
354,2,2
355,2,2
356,2,2
357,2,2
358,2,2
359,2,2
360,2,2
361,2,2
362,2,2
363,2,2
364,2,2
365,2,2
366,3,2
367,3,2
368,3,2
369,3,2
370,3,2
371,3,2
372,3,2
373,3,2
374,3,2
375,3,2
376,3,2
377,1,3
378,1,3
379,1,3
380,1,3
381,1,3
382,1,3
383,1,3
384,1,3
385,1,3
386,1,3
387,1,3
388,1,3
389,1,3
390,1,3
391,1,3
392,1,3
393,1,3
394,1,3
395,1,3
396,1,3
397,1,3
398,1,3
399,1,3
400,1,3
401,1,3
402,1,3
403,1,3
404,1,3
405,1,3
406,1,3
407,1,3
408,1,3
409,1,3
410,1,3
411,1,3
412,1,3
413,1,3
414,1,3
415,1,3
416,1,3
417,1,3
418,1,3
419,1,3
420,1,3
421,1,3
422,1,3
423,1,3
424,1,3
425,1,3
426,1,3
427,1,3
428,1,3
429,1,3
430,1,3
431,1,3
432,1,3
433,1,3
434,1,3
435,1,3
436,1,3
437,1,3
438,1,3
439,1,3
440,1,3
441,1,3
442,1,3
443,1,3
444,1,3
445,1,3
446,1,3
447,1,3
448,1,3
449,1,3
450,1,3
451,1,3
452,1,3
453,1,3
454,1,3
455,1,3
456,1,3
457,1,3
458,1,3
459,1,3
460,1,3
461,2,3
462,2,3
463,2,3
464,2,3
465,2,3
466,2,3
467,2,3
468,2,3
469,2,3
470,2,3
471,2,3
472,2,3
473,3,3
474,3,3
475,3,3
476,3,3
477,3,3
478,3,3
479,1,4
480,1,4
481,1,4
482,1,4
483,1,4
484,1,4
485,1,4
486,1,4
487,1,4
488,1,4
489,1,4
490,1,4
491,1,4
492,1,4
493,1,4
494,1,4
495,1,4
496,1,4
497,1,4
498,1,4
499,1,4
500,1,4
501,1,4
502,1,4
503,1,4
504,1,4
505,1,4
506,1,4
507,1,4
508,1,4
509,1,4
510,1,4
511,1,4
512,1,4
513,1,4
514,1,4
515,1,4
516,1,4
517,1,4
518,1,4
519,1,4
520,1,4
521,1,4
522,1,4
523,1,4
524,1,4
525,1,4
526,1,4
527,1,4
528,1,4
529,1,4
530,1,4
531,1,4
532,1,4
533,1,4
534,1,4
535,1,4
536,1,4
537,1,4
538,1,4
539,1,4
540,1,4
541,1,4
542,1,4
543,1,4
544,1,4
545,1,4
546,1,4
547,1,4
548,1,4
549,1,4
550,1,4
551,1,4
552,1,4
553,1,4
554,1,4
555,1,4
556,1,4
557,1,4
558,1,4
559,1,4
560,1,4
561,1,4
562,1,4
563,1,4
564,1,4
565,1,4
566,1,4
567,1,4
568,1,4
569,1,4
570,1,4
571,1,4
572,1,4
573,1,4
574,1,4
575,1,4
576,1,4
577,1,4
578,1,4
579,1,4
580,1,4
581,1,4
582,1,4
583,1,4
584,1,4
585,1,4
586,1,4
587,1,4
588,1,4
589,1,4
590,1,4
591,1,4
592,1,4
593,1,4
594,1,4
595,1,4
596,1,4
597,1,4
598,1,4
599,1,4
600,1,4
601,1,4
602,1,4
603,1,4
604,1,4
605,1,4
606,1,4
607,2,4
608,2,4
609,2,4
610,2,4
611,2,4
612,2,4
613,2,4
614,2,4
615,2,4
616,2,4
617,2,4
618,2,4
619,2,4
620,2,4
621,2,4
622,2,4
623,3,4
624,3,4
625,3,4
626,3,4
627,3,4
628,3,4
629,3,4
630,3,4
631,1,5
632,1,5
633,1,5
634,1,5
635,1,5
636,1,5
637,1,5
638,1,5
639,1,5
640,1,5
641,1,5
642,1,5
643,1,5
644,1,5
645,1,5
646,1,5
647,1,5
648,1,5
649,1,5
650,1,5
651,1,5
652,1,5
653,1,5
654,1,5
655,1,5
656,1,5
657,1,5
658,1,5
659,1,5
660,1,5
661,1,5
662,1,5
663,1,5
664,1,5
665,1,5
666,1,5
667,1,5
668,1,5
669,1,5
670,1,5
671,1,5
672,1,5
673,1,5
674,1,5
675,1,5
676,1,5
677,1,5
678,1,5
679,1,5
680,1,5
681,1,5
682,1,5
683,1,5
684,1,5
685,1,5
686,1,5
687,1,5
688,1,5
689,1,5
690,1,5
691,1,5
692,1,5
693,1,5
694,1,5
695,1,5
696,1,5
697,2,5
698,2,5
699,2,5
700,2,5
701,2,5
702,2,5
703,2,5
704,2,5
705,2,5
706,2,5
707,2,5
708,3,5
709,3,5
710,3,5
711,3,5
712,3,5
taken_seats:
screening_id,seat_id,user_id
1,176,NULL
1,181,NULL
2,1,NULL
2,4,NULL
2,5,NULL
3,178,NULL
3,179,NULL
3,180,NULL
3,181,NULL
3,200,NULL
I tried to add GROUP BY and it didn't work because i didn't get ordered first.
Also I tried writing a subquery but I didn't succeed in that.

Why do you join all taken seats for all screenings when you are only interested in screening 3? Make sure you join the taken seats for the screening in question.
SET #hall_id = 2;
SET #screening_id = 3;
SELECT
s.id AS seat_id,
st.type_name AS seat_type,
#screening_id AS screening_id,
CASE WHEN ts.screening_id IS NOT NULL
THEN 'Taken'
ELSE 'Not taken'
END AS is_taken
FROM seats s
JOIN seat_types st ON seats.type_id = seat_types.id
LEFT JOIN taken_seats ts ON ts.seat_id = s.id AND ts.screening_id = #screening_id
WHERE s.hall_id = #hall_id
ORDER BY s.id;

You could try joining the table as sql expressions
SELECT * FROM table1
LEFT JOIN (
SELECT * FROM another ORDER BY something
) as table2
ON table1.id = table2.id
GROUP BY something
Not sure if that structure is correct but that's what I would do.

Didnt display results in database

I have a little problem with one database. I have already entered data in the individual tables in the database. The problem is that with this code, it displays the column names, but didnt return rows. I can't find the error. I think the problem is in JOIN itself. Any ideas for solving the problem?
SELECT cars.brand,
cars.model,
cars.yearofproduction,
cars.engine_type,
parts.part_name,
parts.price AS MONEY,
parts.quantity
FROM CATALOG
JOIN parts
ON parts.part_name = parts.id
JOIN cars
ON CATALOG.car_id = cars.id
WHERE quantity >= '0'
HAVING MONEY < (
SELECT AVG(price)
FROM cars
);
And here the tables. I've already insert values in the tables.
CREATE TABLE CATALOG.parts
(
id INT AUTO_INCREMENT PRIMARY KEY,
part_name VARCHAR(255) NOT NULL,
price DECIMAL NOT NULL,
DESCRIPTION VARCHAR(255) DEFAULT NULL,
quantity TINYINT DEFAULT 0
);
CREATE TABLE CATALOG.cars
(
id INT AUTO_INCREMENT PRIMARY KEY,
brand VARCHAR(255) NOT NULL,
model VARCHAR(255) NOT NULL,
yearofproduction YEAR NOT NULL,
engine_type SET('Diesel', 'A95', 'Gas', 'Metan')
);
CREATE TABLE CATALOG.catalog
(
part_id INT NOT NULL,
CONSTRAINT FOREIGN KEY(part_id) REFERENCES parts(id)
ON DELETE RESTRICT ON UPDATE CASCADE,
car_id INT NOT NULL,
CONSTRAINT FOREIGN KEY(car_id) REFERENCES cars(id)
ON DELETE RESTRICT ON UPDATE CASCADE,
PRIMARY KEY(part_id, car_id)
);

MYSQL Select One Row With Less

I'm making a database for a unit and I need a query that selects the vet with less appointments assigned so I can assign the next appointment to him or her. I don't know how to start, but I'm pretty sure I'll have to use variables here. Those are my tables:
CREATE TABLE IF NOT EXISTS staff (
stafId MEDIUMINT UNSIGNED AUTO_INCREMENT,
stafAdd VARCHAR(150) NOT NULL,
stafConNum VARCHAR(15) NOT NULL,
stafEma VARCHAR(40) NOT NULL,
stafFirNam VARCHAR(20) NOT NULL,
stafLasNam VARCHAR(30) NOT NULL,
stafPos ENUM('nurse', 'vet') NOT NULL,
PRIMARY KEY (stafId)
) engine = InnoDB;
CREATE TABLE IF NOT EXISTS vet (
vetId MEDIUMINT UNSIGNED AUTO_INCREMENT,
FOREIGN KEY (vetId) REFERENCES staff(stafId),
PRIMARY KEY (vetId)
) engine = InnoDB;
CREATE TABLE IF NOT EXISTS appointment (
appoId MEDIUMINT UNSIGNED AUTO_INCREMENT,
appoDat DATETIME NOT NULL,
appoPetId MEDIUMINT UNSIGNED,
FOREIGN KEY (appoPetId) REFERENCES pet(petId),
appoVetId MEDIUMINT UNSIGNED,
FOREIGN KEY (appoVetId) REFERENCES vet(vetId),
PRIMARY KEY (appoId)
) engine = InnoDB;

You should start by looking up the mysql MIN() function. Follow that up with learning about JOINs and you'll be breezing through this.

You could get the vet's with the number of appointment like this:
SELECT
*
FROM
(
SELECT
vet.vetId,
COUNT(*) AS nbrOfAppointment
FROM
vet
JOIN appointment
ON vet.vetId = appointment.appoVetId
) AS tbl
ORDER BY tbl.nbrOfAppointment ASC

This Request gives you the number of appointement per vet ordered by number of appointement.
Select vet.id, count(*) as nb_appointement
from vet
inner join appointement app on vet.vetId = app.appoVetId
group by vet.id
order by nb_appointement asc

Join table on already joined table

I'm struggling to put together a select statement that joins 3 tables.
Here's the database:
CREATE TABLE Beerstyles
(
style_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
style_name VARCHAR(50) NOT NULL
)ENGINE=InnoDB;
CREATE TABLE Breweries
(
brew_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
booth_num VARCHAR(10) NOT NULL,
brew_name VARCHAR(50) NOT NULL
)ENGINE=InnoDB;
CREATE TABLE Beers
(
beer_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
beer_name VARCHAR(50) NOT NULL,
alc_vol DECIMAL(2,1) NOT NULL,
fk_style_id INT NOT NULL,
fk_brew_id INT NOT NULL
)ENGINE=InnoDB;
CREATE TABLE Favorites
(
fav_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
user_id VARCHAR(55) NOT NULL,
fk_beer_id INT NOT NULL,
fav_comment VARCHAR(255)
)ENGINE=InnoDB;
ALTER TABLE Beers ADD CONSTRAINT FK_BeerStyle_Style FOREIGN KEY (fk_style_id) REFERENCES Beerstyles (style_id);
ALTER TABLE Beers ADD CONSTRAINT FK_BeerBrew_Brew FOREIGN KEY (fk_brew_id) REFERENCES Breweries (brew_id);
ALTER TABLE Favorites ADD CONSTRAINT FK_FavBeer_Beer FOREIGN KEY (fk_beer_id) REFERENCES Beers (beer_id);
And here's the first part:
SELECT * FROM Favorites JOIN Beers ON Favorites.fk_beer_id = Beers.beer_id
I need to mix in the brew_name, but haven't been able to get it right. When I try to join Breweries (ON Favorites.fk_brew_id = Breweries.brew_id) i get an error saying "Unknown column 'Favorites.fk_brew_id' in 'on clause'"
Hope you guys can help me out :)

There is no fk_brew_id in the Favorite table, but you have to add the JOIN condition to the Beers table not to the Favorite table like this:
SELECT
bw.brew_name,
b.beer_name,
f.fav_comment,
...
FROM Favorites AS f
INNER JOIN Beers AS b ON f.fk_beer_id = b.beer_id
INNER JOIN Breweries AS bw ON b.fk_brew_id = bw.brew_id;

SELECT *
FROM Favorites
JOIN Beers
ON Favorites.fk_beer_id = Beers.beer_id
JOIN Breweries
ON Beers.fk_brew_id = Breweries.brew_id
Of course is real life you shoudl never use select *. When you have a join you are repeating columns and causing your query to be slower.