I am trying to put together a SQL statement which pulls the names of employees that have a certain title and how many labor hours that they currently have in total for a total of the current week. I am working with two different tables, so I assume that I would need to use JOIN in this case, however my dilemma is that I would need to join two fields from TABLE A to one field on TABLE B. Is this possible?
See below for my code (so far):
public function get_all_techs_with_hours()
{
// get all technicians
$this->db->select('*');
$this->db->from('employees');
$this->db->where('role', 'Body Technician');
$this->db->or_where('role', 'Paint Technician');
$this->db->or_where('role', 'Combo Technician');
$query = $this->db->get();
return $query;
}
In this case, employees is TABLE A and jobs is TABLE B. I need to JOIN TABLE B to TABLE A based on jobs.body_tech matching employees.first_name and employees.last_name. Atleast, I think I do. I'm sure I'm going about this the hardest approach possible, but I can't seem to find any helpful manual to learn how to do this. In the end, all I would like to do is combine all hours for each technician and add to the same array using two different tables.
Related
I have two queries that I need to run to obtain, a list of contracts and a list of sales, due to the fact that there is a duplicate contract for each customer I have written a query that will return customer_id and the date of their final contract while joining on our products table to filter for certain products. another query returns a list of sales for a given area by connecting to a couple of tables as well is their anyway after calling these queries I could join them using php .
$contracts = DB::table('contracts as c').....
$leads= DB::table('contracts as l')..
so after creating these two collections that both have the column customer_id, i want to join them using PHP if these where both tables in my database this would be a simple left_join, however, I can't figure out a way to do it with the output of the quarry .... thanks in advance for all the help. I have been doing some research and think i need to map somehow
$leads = $leads->map(function ($item, $key) {
$single_lead = $contract->where('l.customer_id',$item->spp.customer_id);
return collect($item)->merge($single_lead);
something like this but this is not working and I'm stuck so I should be going through each item in leads and then merge it with the contract information that has the same customer_id
Your question wasn't very clear but giving you a hint to do left join,
You can do it as:
$query = DB::table('contracts')->leftJoin('customer','customer.id','=','contracts.customer_id')->get()
You can see it in the Laravel Docs
I'm building a query to show items with user and then show highest Bid on the item.
Example:
Xbox 360 by james. - the highest bid was $55.
art table by mario. - the highest bid was $25.
Query
SELECT i, u
FROM AppBundle:Item i
LEFT JOIN i.user u
I have another table bids (one to many relationship). I'm not sure how can I include single highest bid of the item in the same query with join.
I know I can just run another query after this query, with function (relationship), but I'm avoiding to do that for optimisation reasons.
Solution
SQL
https://stackoverflow.com/a/16538294/75799 - But how is this possible in doctrine DQL?
You can use IN with a sub query in such cases.
I am not sure if I understood your model correctly, but I attempted to make your query with a QueryBuilder and I am sure you will manage to make it work with this example:
$qb = $this->_em->createQueryBuilder();
$sub = $qb;
$sub->select('mbi') // max bid item
->where('i.id = mbi.id')
->leftJoin('mbi.bids', 'b'))
->andWhere($qb->expr()->max('b.value'))
->getQuery();
$qb = $qb->select('i', 'u')
->where($qb->expr()->in('i', $sub->getDQL()))
->leftJoin('i.user', 'u');
$query = $qb->getQuery();
return $query->getResult();
Your SQL query may look something like
select i,u
from i
inner join bids u on i.id = u.item_id
WHERE
i.value = (select max(value) from bids where item_id = i.id)
group by i
DQL, I don't think supports subqueries, so you could try using a Having clause or see if Doctrine\ORM\Query\Expr offers anything.
To solve this for my own case, I added a method to the origin entity (item) to find the max entity in a list of entities (bids), using Doctrine's Collections' Criteria I've written about it here.
Your Item entity would contain
public function getMaxBid()
{
$criteria = Criteria::create();
$criteria->orderBy(['bid.value' => Criteria::ASC]);
$criteria->setLimit(1);
return $this->bids->matching($criteria);
}
Unfortunately, there's no way that i know to find the maximum bid and the bidder with one grouping query, but there's several techniques to making the logic work with several queries. You could do a sub select and that might work fine depending on the size of the table. If you're planning on growing to the point where that's not going to work, you're probably already looking at sharing your relational databases, moving some data to a less transactional, higher performance db technology, or denormalizing, but if you want to keep this implemented in pure MySQL, you could use a procedure to express in multiple commands how to check for a bid and optionally add to the list, also updating the current high bidder in a denormalized high bids table. This keeps the complex logic of how to verify the bid in one, the most rigorously managed place - the database. Just make sure you use transactions properly to stop 2 bids from being recorded concurrently ( eg, SELECT FOR UPDATE).
I used to ask prospective programmers to write this query to see how experienced with MySQL they were, many thought just a max grouping was sufficient, and a few left the interview still convinced that it would work fine and i was wrong. So good question!
I am building a simple adress book website where you can enter information about a person and then enter information about adresses. You can then select where people lives using a drop down menu to update the building id attribute in the person to match the automaticly generated id in the building. What I can't figure out how to do print all info about all persons(this I can do) and then print the info about the building that matches each persons building id(this I have no idea how to do. Right now I am using a while loop to print each person. But I can't get the matching building to print.
Edit: also, thanks for all info I have gotten from this site in my learning of webbprograming
You could use joins in SQL to combine several tables in one query. Also you could use GROUP BY.
Just search for that and I think you will get a good tutorial in your language.
Here are some good links:
SQL JOIN, SQL GROUP BY
Could use some code and table names to help define this example a little better, but regardless, you need to change your mysql query. In your database you need at least 1 matching row between your persons table and your buildings table. This way you can JOIN them together using the common row.
I will be using id as a placeholder for the common row in this example. Somethings like this should work:
SELECT * FROM persons LEFT JOIN buildings ON(persons.id=buildings.id) WHERE persons.building_id = buildings.building_id
To get all the results from persons and buildings you will need a separate query. But, the query above should give you the results of the person's info where the building_id matches the building_id from buildings.
specs: PHP 5 with mySQL built on top of Codeigniter Framework.
I have a database table called game and then sport specific tables like soccerGame and footballGame. these sport specific tables have a gameId field linking back to the game table. I have corresponding classes game and soccerGame/footballGame, which both extend game.
When I look up game information to display to the user, I'm having trouble figuring out how to dynamically link the two tables. i'm curious if it's possible to get all the information with with one query. The problem is, I need to query the game table first to figure out the sport name.
if that's not possible, my next thought is to do it with two queries. have my game_model query the game table, then based off the sport name, call the appropriate sport specific model (i.e. soccer_game_model) and get the sport specific info.
I would also pass the game object into the soccer_model, and the soccer_model would use that object to build me a soccerGame object. this seems a little silly to me because i'm building the parent object and then giving it to the extending class to make a whole new object?
thoughts?
thanks for the help.
EDIT:
game table
gameId
sport (soccer, basketball, football, etc)
date
other data
soccerGame table
soccerGameId
gameId
soccer specific information
footballGame table
footballGameId
gameId
football specific information
and so on for other sports
So I need to know what the sport is before I can decide which sport specific table I need to pull info from.
UPDATE:
Thanks all for the input. It seems like dynamic SQL is only possible through stored procedures, something I'm not well versed on right now. And even with them it's still a little messy. Right now I will go the two query route, one to get the sport name, and then a switch to get the right model.
From the PHP side of things now, it seems a little silly to get a game object, pass it to, say, my soccer_game_model, and then have that return me a soccer_game object, which is a child of the original game. Is that how it has to be done? or am I missing something from an OO perspective here?
To extend on Devin Young's answer, you would achieve this using Codeigniter's active record class like so:
public function get_game_by_id($game_id, $table)
{
return $this->db->join('game', 'game.id = ' . $table . '.gameId', 'left')
->where($table . '.gameId', $game_id)
->get('game')
->result();
}
So you're joining the table by the gameId which is shared, then using a where clause to find the correct one. Finally you use result() to return an array of objects.
EDIT: I've added a second table paramater to allow you to pass in the name of the table you can join either soccerGame, footballGame table etc.
If you don't know which sport to choose at this point in the program then you may want to take a step back and look at how you can add that so you do know. I would be reluctant to add multiple joins to all sport tables as you''ll run into issues down the line.
UPDATE
Consider passing the "sport" parameter when you look up game data. As a hidden field, most likely. You can then use a switch statement in your model:
switch($gameValue) {
case 'football': $gameTable = "footballGame"; break;
case 'soccer': $gameTable = "soccerGame"; break;
}
Then base your query off this:
"SELECT *
FROM ". $gameTable . "
...etc
You can combine the tables with joins. http://www.w3schools.com/sql/sql_join.asp
For example, if you need to get all the data from game and footballGame based on a footballGameId of 15:
SELECT *
FROM footballGame a
LEFT OUTER JOIN game b ON a.id = b.gameId
WHERE footballGameId = 15
Check this Stack Overflow answer for options on how to do it via a standard query. Then you can turn it into active record if you want (though that may be complicated and not worth your time if you don't need DB-agnostic calls in your app).
Fow what it's worth, there's nothing wrong with doing multiple queries, it just might be slower than an alternative. Try a few options, see what works best for you and your app.
I have a system where a user is part of a series of "runs", to each "run", can be added courses, teachers(users), classes and so on.
Each teacher(user) has chosen his/her classes & courses.
Here's a run-down of the tables I have that are relevant:
lam_run - The run in it self.
lam_run_course - Relational table that shows what runs has what courses
lam_teacher_course - Relational table that shows which teacher has which courses
lam_run_teacher - Relational table that shows what teachers are in what courses
What I want to do is show each teacher which runs that are relevant to them (based on which courses they have selected seen in lam_teacher_course) but in which they are not already participating.
Here's the MySQL code I have so far that does not work:
$query_relevant_runs = "
SELECT DISTINCT
lam_run_course.run_id
FROM
lam_teacher_course,
lam_run_course,
lam_run, lam_run_teacher
WHERE
lam_teacher_course.user_id = '1'
AND
lam_teacher_course.course_id = lam_run_course.course_id
AND
lam_run_teacher.user_id != '1'";
Instead this code shows all runs that are relevant, but it doesn't exclude the runs the user is already in..
What can I do to fix this?
Ps. Sorry for bad title, no idea what I should've called it :S
Here is a link to part of the databases (the relevant part): Link!
I think what you're looking for is:
LEFT JOIN `lam_run_teacher` `lam_run_teach_exclude`
ON `lam_run_teacher_exclude`.`user_id` = `lam_teacher_user`.`user_id`
...
WHERE `lam_run_teacher`.`user_id` IS NULL
The LEFT JOIN takes your current query, and appends the additional data to it. However, unlike the INNER JOIN you are using now (using the kinda-strange multiple-from syntax), the LEFT JOIN does not limit your resultset to just those where there is data for the righthand side. The righthand columns will be NULL. By filtering on that NULL, you can find all runs that are interesting, and for which there is not yet a relation to the teacher.
Does this help?
I'd recommend always using the normal join syntax (INNER JOIN target on target.id = source.id) - that way you're more aware of the idea that there are other kinds of join as well, and all your joins will look identical. It takes some getting used to, but definitely helps when your queries get more complex.
Also, in your cross-referencing tables, you can drop the primary key columns. If the only purpose of a table is to define a link between two tables, make the primary key consist of the two keys you've got. Unless you want to be able to related the same teacher to a run multiple times...
OK, took me way longer than it should have, but here's the complete thing:
SELECT
DISTINCT `lam_run_course`.run_id
FROM
`lam_run_course`
INNER JOIN
`lam_teacher_course`
ON `lam_teacher_course`.course_id = `lam_teacher_course`.course_id
LEFT JOIN
`lam_run_teacher` ON (`lam_run_teacher`.`run_id` = `lam_run_course`.`run_id` AND `lam_run_teacher`.`user_id` = 3)
WHERE
`lam_teacher_course`.user_id = 3
and `lam_run_teacher`.`run_id` IS NULL