Using Sequel I'd like to create an UPDATE statement like the following (from Postgres docs)
UPDATE employees SET sales_count = sales_count + 1 FROM accounts
WHERE accounts.name = 'Acme Corporation'
AND employees.id = accounts.sales_person;
However, looking at the Sequel documentation it's not clear where there's any way to create the FROM clause.
Is there a way to do this?
Thanks!
OK, Ben Lee's answer got me going in the right direction. Solution:
DB[:employees].from(:employees, :accounts).
where(:accounts__name => 'Acme Corporation').
update_sql(:employees__sales_count => "employees.sales_count + 1".lit)
I'm a bit uncertain about the use of .lit here, but it does seem to do the trick. (Also, I'm using update_sql rather than update to produce the SQL output rather than running the command.)
Result, as desired:
UPDATE "employees"
SET "employees"."sales_count" = employees.sales_count + 1
FROM "accounts"
WHERE ("accounts"."name" = 'Acme Corporation')
Everybody else's answers have one tiny superfluous clause.
DB.from(:employees, :accounts).
where(:accounts__name => 'Acme Corporation').
update_sql(:employees__sales_count => "employees.sales_count + 1".lit)
If you're doing a from() with two tables, then the one inside the DB[...] is ignored.
Can you just use a regular join? It's not exactly your query, but it should accomplish your goals, right?
DB[:employees].left_outer_join(:accounts, :sales_person => :id).
where('accounts.name' => 'Acme Corporation').
update('employees.sales_count' => 'employees.sales_count' + 1)
Related
I am trying to build a case query with distinct count in cakephp 3.
This is the query in SQL:
select COUNT(distinct CASE WHEN type = 'abc' THEN app_num END) as "count_abc",COUNT(distinct CASE WHEN type = 'xyz' THEN app_num END) as "count_xyz" from table;
Currently, I got this far:
$query = $this->find();
$abc_case = $query->newExpr()->addCase($query->newExpr()->add(['type' => 'abc']),' app_num','string');
$xyz_case = $query->newExpr()->addCase($query->newExpr()->add(['type' => 'xyz']),'app_num','string');
$query->select([
"count_abc" => $query->func()->count($abc_case),
"count_xyz" => $query->func()->count($xyz_case),
]);
But I can't apply distinct in this code.
Using keywords in functions has been a problem for quite some time, see for example this issue ticket: https://github.com/cakephp/cakephp/issues/10454.
This has been somewhat improved in https://github.com/cakephp/cakephp/pull/11410, so that it's now possible to (mis)use a function expression for DISTINCT as kind of a workaround, ie generate code like DISTINCT(expression), which works because the parentheses are being ignored, so to speak, as DISTINCT is not a function!
I'm not sure if this works because the SQL specifications explicitly allow parentheses to be used like that (also acting as a whitespace substitute), or because it's a side-effect, so maybe check that out before relying on it!
That being said, you can use the workaround from the linked PR until real aggregate function keyword support is being added, ie do something like this:
"count_abc" => $query->func()->count(
$query->func()->DISTINCT([$abc_case])
)
This would generate SQL similar to:
(COUNT(DISTINCT(CASE WHEN ... END)))
How can I transform this sql to codeigniter query? I have screenshot of an EER diagram to help you understand better. So there are three tables to join. I guess, one is "pjesma", then "izvodjac", and "izvodi_pjesmu". This sql works when I run it and gives me results I want. I am also using pagination so I need limit and offset somehow included.
SELECT pjesma_id, naslov, naziv
FROM pjesma p, izvodjac i, izvodi_pjesmu ip
WHERE p.pjesma_id = ip.pjesma_pjesma_id
AND i.izvodjac_id = ip.izvodjac_izvodjac_id
in model:
public function paginacija_pjesme($limit, $offset) {
$this->db->select('pjesma_id', 'naslov', 'naziv');
$this->db->from('pjesma p');
$this->db->join('izvodi_pjesmu ip', 'p.pjesma_id=ip.pjesma_pjesma_id');
$this->db->join('izvodjac i', 'i.izvodjac_id=ip.izvodjac_izvodjac_id');
$this->db->limit($limit, $offset);
$query = $this->db->get();
return $query->result();
}
EDIT:
So in select I used wrong syntax, this line:
$this->db->select('pjesma_id', 'naslov', 'naziv');
should be like this:
$this->db->select('pjesma_id, naslov, naziv');
A few things, as you are dealing with objects within the query builder class, you can method-chain and make things a little less cluttered.
You are maybe getting an ambiguous column error, joining and not prefixing your select. Hard to tell without the error being posted you are facing.
Always best to (just in case) set defaults to your method arguments as well, in case you pass a blank variable (or don't need to for whatever reason).
When you are using multiple tables in the FROM statement you are actually doing a CROSS JOIN, and your new code is giving INNER JOIN,trying the join syntax direct to your SQL server might help as you are not actually doing the same thing between your first written query, and the codeigniter one..
Try the below with LEFT join just to see... If there are NULL joins using INNER they will be omitted
public function paginacija_pjesme($limit = 10, $offset = 0) {
$query = $this->db->select('p.pjesma_id, p.naslov, i.naziv')
->from('pjesma p')
->join('izvodi_pjesmu ip', 'p.pjesma_id = ip.pjesma_pjesma_id', 'left')
->join('izvodjac i', 'i.izvodjac_id = ip.izvodjac_izvodjac_id', 'left')
->limit($limit, $offset)
->get();
return $query->result();
}
Are you getting any errors? what do you see if you print_r($query->result()) ?
try also spitting out $this->db->last_query() - this will output the SQL codeigniter has build. Then running this directly to your database, and see the results from there. You might even see the issue without needing to run it.
This is an example of what your current codeigniter code is generating (as you can see, different to your original query):
SELECT pjesma_id, naslov, naziv
FROM pjesma p
INNER JOIN izvodi_pjesmu ip ON p.pjesma_id = ip.pjesma_pjesma_id
INNER JOIN izvodjac i ON i.izvodjac_id = ip.izvodjac_izvodjac_id
# LIMIT 10,0
In a where statement, you can use variables like:
Order.where('employee_id = ?', params[:employee_id])
I'm trying to accomplish something similar with a select, but it's not working:
Order.select('amount FROM line_items WHERE employee_id = ? AS employee_line_items', params[:employee_id])
=> ERROR: syntax error at or near "1"
=> LINE 1: ...ployee_id" = ? AS employee_line_items, 1
What's going on here? Is it possible to use ? in select statement? If not, how can you insert an escaped sql string here? I'd like to just use #{params[:employee_id]}, but this bit of code would be vulnerable to sql injection.
You have to split your query and chain it:
Order.select('amount FROM line_items').where(['WHERE employee_id = ?', params[:employee_id]])
And also based on this question, I believe you cannot use AS in WHERE clause, only when selecting fields (and you can't use them in WHERE in any case)
Check the documentation to understand how select works on ActiveRecord models
What I basically want to do is the following:
a = Assignment.all(:conditions => { :end_date < :start_date })
I only want to select those records on which the end_date is before the start_date.
I actually don't want ending up writing a
for each, push to array if end_date is earlier than start_date.
How can I achieve this in a pretty 'Railsy'-way?
Thank you in advance.
Edit:
I think the problem is comparing the values of both columns. (Allmost) every query is comparing a cell-value to an input-value.
This is a shot in the dark, but maybe one in the right direction ?
Haven't figured out a solution.
It's been a while here but nevertheless, you can just use the ArelTable method:
t = Assignment.arel_table
Assignment.where(t[:end_date].lt(t[:start_date]))
The condition predicates documentation: http://www.rubydoc.info/github/rails/arel/Arel/Predications
The ArelTable documentation: http://www.rubydoc.info/github/rails/arel/Arel/Table
And a good guide: http://jpospisil.com/2014/06/16/the-definitive-guide-to-arel-the-sql-manager-for-ruby.html
a = Assignment.all(:conditions => ["end_date < ?", :start_date ])
Check this: http://api.rubyonrails.org/classes/ActiveRecord/FinderMethods.html#method-i-all
I am assuming that you are using ActiveRecord
try
a = Assignment.where('regioassignments.end_date < regioassignments.start_date')
use the tablename followed by the EXACT COLUMNNAMES in the database, since ActiveRecord recognizes this and uses this as SQL directly.
That means the columnname for end_date is probably assignment_expected_end_date from what I figured from one of your comments.
adapted from this answer
I have several complex queries (using subqueries, etc...) and want to glue them together with OR or AND statement.
For example:
where1=table.where(...)
where2=table.where(...)
I would like something like
where3=where1.or where2
Next example doesn't work for me:
users.where(users[:name].eq('bob').or(users[:age].lt(25)))
because of I have several where(..) queries and I want to concatenate them.
In other words
I have 3 methods: first return first where, second-second, third - OR concatenation.
I must have able to use all 3 methods in my application and save DRY code
are you looking for the form:
users.where(users[:name].eq('bob').or(users[:age].lt(25)))
docs: https://github.com/rails/arel
users.where(users[:name].eq('bob').or(users[:age].lt(25))) is close, but you need to get the arel_table to specify the columns, e.g.
t = User.arel_table
User.where(t[:name].eq('bob').or(t[:age].lt(25)))
I know that for AND concatenation you can do:
users = User.where(:name => 'jack')
users = users.where(:job => 'developer')
and you get a concatenation with AND in SQL (try it with #to_sql at the end)
Other than that you can do:
where1=table.where(...)
where2=table.where(...)
where1 & where2
example:
(User.where(:name => 'jack') & User.where(:job => 'dev')).to_sql
=> "SELECT `users`.* FROM `users` WHERE `users`.`name` = 'jack' AND `users`.`job` = 'dev'"