Understanding MySql queries - mysql

Question

Trying to teach my self a bit of mysql and php and decided to do that by working on actual project with help oh "how to do everything with MySQL and PHP book".
first problem i have is with understanding joint table queries.
here are my tables:
CREATE TABLE `clients` (
`id` SMALLINT(6) NOT NULL AUTO_INCREMENT,
`client` VARCHAR(50) NULL DEFAULT NULL,
PRIMARY KEY (`id`),
INDEX `KlientID` (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=8;
CREATE TABLE `facilities` (
`id` SMALLINT(6) NOT NULL AUTO_INCREMENT,
`facility` VARCHAR(45) NOT NULL,
`fk_client` SMALLINT(6) NULL DEFAULT NULL,
PRIMARY KEY (`id`),
INDEX `fk_idklijent_idx` (`fk_client`),
CONSTRAINT `FK_client_id` FOREIGN KEY (`fk_client`) REFERENCES `clients` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=35;
CREATE TABLE `models` (
`id` SMALLINT(6) NOT NULL AUTO_INCREMENT,
`model` VARCHAR(50) NOT NULL,
`fk_manufacturer` SMALLINT(6) NOT NULL,
PRIMARY KEY (`id`),
INDEX `ModelID` (`id`),
INDEX `fk_proizvodjacID_idx` (`fk_manufacturer`),
CONSTRAINT `FK_manuf_id` FOREIGN KEY (`fk_manufacturer`) REFERENCES `manufacturers` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=9;
CREATE TABLE `machines` (
`id` SMALLINT(6) NOT NULL AUTO_INCREMENT,
`serial` VARCHAR(50) NOT NULL,
`fk_model` SMALLINT(6) NOT NULL,
`InvBr` INT(11) NULL DEFAULT '0',
`fk_facilities` SMALLINT(6) NULL DEFAULT '0',
`sw` VARCHAR(255) NULL DEFAULT NULL,
`adaptation` VARCHAR(255) NULL DEFAULT NULL,
PRIMARY KEY (`id`),
INDEX `FK_uredjaji_modeli` (`fk_model`),
INDEX `FK_uredjaji_poslovnice` (`fk_facilities`),
INDEX `Index 4` (`serial`),
CONSTRAINT `FK_facility_id` FOREIGN KEY (`fk_facilities`) REFERENCES `facilities` (`id`) ON UPDATE CASCADE ON DELETE CASCADE,
CONSTRAINT `FK_models_id` FOREIGN KEY (`fk_model`) REFERENCES `models` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=93;
CREATE TABLE `technicians` (
`id` SMALLINT(6) NOT NULL AUTO_INCREMENT,
`name` VARCHAR(50) NULL DEFAULT NULL,
PRIMARY KEY (`id`),
INDEX `ServiserID` (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=5;
CREATE TABLE `workorders` (
`id` SMALLINT(6) NOT NULL AUTO_INCREMENT,
`wo_nr` VARCHAR(50) NOT NULL,
`fk_machine_id` SMALLINT(6) NOT NULL,
`fk_technitian_id` SMALLINT(6) NOT NULL,
`counter` INT(11) NOT NULL DEFAULT '0',
`service_date` DATE NOT NULL,
`description` LONGTEXT NOT NULL,
`work_hours` INT(11) NOT NULL DEFAULT '1',
PRIMARY KEY (`id`),
INDEX `FK_rn_serviseri` (`fk_technitian_id`),
INDEX `FK_machines_id_idx` (`fk_machine_id`),
CONSTRAINT `FK_machines_id` FOREIGN KEY (`fk_machine_id`) REFERENCES `machines` (`id`) ON UPDATE NO ACTION ON DELETE NO ACTION,
CONSTRAINT `FK_technitian_id` FOREIGN KEY (`fk_technitian_id`) REFERENCES `technicians` (`id`) ON UPDATE NO ACTION ON DELETE NO ACTION
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
AUTO_INCREMENT=1393;
using this query i get each row 8 times.
SELECT DATE_FORMAT (w.service_date, '%d.%m.%Y'), f.facility, m.model, mc.serial, w.description, t.name
FROM workorders AS w, facilities AS f, models AS m, machines AS mc, technicians AS t
WHERE f.id = mc.fk_facilities AND w.fk_machine_id = mc.id AND w.fk_technitian_id = t.id AND w.service_date > '2009-12-31'
ORDER BY w.service_date DESC;
can someone pls point me to what i'm doing wrong. i only need rows from workorders table. other tables are here only to show real data not only id's - bad, not true :(
thx
edit 1:
i need a list of workorders. to explain my question little more here is how the result should look like:
[date][name of the facility the machine (fk_machine_id) belongs to][model of the machine (fk_machine_id)][serial number of the machine (fk_machine_id)][description from workorder][technician name (fk_technician_id)]
edit2:
here is the model image
i think my problem is in fact that to get the model i need to check with machines table first. Same thing with facility.

Answer 1

got it!
the problem was in one missing AND.
final SELECT looks like this:
SELECT DATE_FORMAT (w.service_date, '%d.%m.%Y') AS service_date, w.wo_nr, f.facility, m.model, mc.serial, FORMAT (w.counter, 0) AS Counter, w.description, t.name AS technician
FROM workorders AS w, technicians AS t, machines AS mc, models AS m, facilities AS f
WHERE mc.fk_facilities = f.id
AND w.fk_machine_id = mc.id
AND mc.fk_model = m.id
AND w.fk_technitian_id = t.id
AND w.service_date > '2009-12-31'
ORDER BY w.service_date DESC;
thx all. moving on to the next problem :)

Answer 2

to get only rows from workorders table use this query
SELECT w.*
FROM workorders AS w, facilities AS f, models AS m, machines AS mc, technicians AS t
WHERE f.id = mc.fk_facilities AND w.fk_machine_id = mc.id AND w.fk_technitian_id = t.id AND w.service_date > '2009-12-31'
ORDER BY w.service_date DESC;

Answer 3

You say you only want data from the workorders table. Then you don't need all the other joins.
SELECT * FROM workorders WHERE service_date > '2009-12-31'
Unless you need the columns in their tables as well.
Not too sure exactly what you require though.

Answer 4

Only put the columns you want returned in your results set in the SELECT section of your query. You can still include columns from other tables in your joins, they just won't be displayed. Also if you are getting multiple rows then either your data contains duplicates in which case you should look at your keys and constraints or you are missing one or more joins.

Answer 5

Would this work for you?
SELECT DISTINCT DATE_FORMAT (w.service_date, '%d.%m.%Y') as service_date,
f.facility, m.model, mc.serial, w.description, t.name
FROM workorders AS w, facilities AS f, models AS m, machines AS mc, technicians AS t
WHERE f.id = mc.fk_facilities
AND w.fk_machine_id = mc.id
AND w.fk_technitian_id = t.id
AND w.service_date > '2009-12-31'
ORDER BY w.service_date DESC;