I'm calling the database based on the criteria passed from the view, so it has to be dynamic.
Let's say I have 2 arrays:
columns = ['col1', 'col2', 'col3']
vals = ['val1', 'val2', val3']
The query is easy to create, I can do concatenation, like
query = columns[0] + " = (?) AND" + ...
But what about the parameters?
#finalValues = MyTable.find(:all, :conditions => [query, vals[0], vals[1]... ])
But I don't know how many parameters I will receive. So while the query problem is solved with a for loop and concatenation, can I do something like:
#finalValues = MyTable.find(:all, :conditions => [query, vals])
And rails will understand that I'm not passing an array for an IN (?) clause, but to split the values for every individual (?)?
Or is my only option to do a full raw string and just go with it?
you can create condition array with query as first element and append all val element to it.
query = columns.map {|col| "#{col} = ?"}.join(" AND ")
#finalValues = MyTable.find(:all, :conditions => [query, *vals])
point of caution the columns and vals should have equal number of elements.
Related
I made two requests. The first one gives me 2419 results and I store the result in $requestFirst. The second, 1 result and I store the result in $requestTwo.
I make a union :
$requestTot = $requestFirst->union($requestTwo);
The total of the $requestTot is 2420 results so all is well so far.
Then :
$request = $this->paginate($requestTot);
$this->set(compact('request'));
And here I don't understand, on each page of the pagination I find the result of $requestTwo. Moreover the pagination displays me :
Page 121 of 121, showing 20 record(s) out of 2,420 total
This is the right number of results except that when I multiply the number of results per page by the number of pages I get 2540. This is the total number of results plus one per page.
Can anyone explain?
Check the generated SQL in Debug Kit's SQL panel, you should see that the LIMIT AND OFFSET clauses are being set on the first query, not appended as global clauses so that they would affect the unionized query.
It will look something like this:
(SELECT id, title FROM a LIMIT 20 OFFSET 0)
UNION
(SELECT id, title FROM b)
So what happens then is that pagination will only be applied to the $requestFirst query, and the $requestTwo query will be unionized on top of it each and every time, hence you'll see its result on every single page.
A workaround for this current limitation would be to use the union query as a subquery or a common table expression from which to fetch the results. In order for this to work you need to make sure that the fields of your queries for the union are being selected without aliasing! This can be achieved by either using Table::subquery():
$requestFirst = $this->TableA
->subquery()
->select(['a', 'b'])
// ...
$requestTwo = $this->TableB
->subquery()
->select(['c', 'd'])
// ...
or by explicitly selecting the fields with aliases equal to the column names:
$requestFirst = $this->TableA
->find()
->select(['a' => 'a', 'b' => 'b'])
// ...
$requestTwo = $this->TableB
->find()
->select(['c' => 'c', 'd' => 'd'])
// ...
Then you can safely use those queries for a union as a subquery:
$union = $requestFirst->union($requestTwo);
$wrapper = $this->TableA
->find()
->from([$this->TableA->getAlias() => $union]);
$request = $this->paginate($wrapper);
or as a common table expression (in case your DBMS supports them):
$union = $requestFirst->union($requestTwo);
$wrapper = $this->TableA
->find()
->with(function (\Cake\Database\Expression\CommonTableExpression $cte) use ($union) {
return $cte
->name('union_source')
->field(['a', 'b'])
->query($union)
})
->select(['a', 'b'])
->from([$this->TableA->getAlias() => 'union_source']);
$request = $this->paginate($wrapper);
I have a cell array that I call "Table", as in the code below (but my array has more lines). Column 1 contains dates in string format. I want to add an additional column that contains the dates in datetime format. I did the following, which works, but it is VERY slow. What are the alternatives?
% Table that I have:
Table{1,1} = 'Stringdate';
Table{2,1} = '01.01.1999';
Table{3,1} = '02.01.1999';
Table{4,1} = '03.01.1999';
Table{5,1} = '04.01.1999';
% What I want to add:
Table{1, size(Table,2)+1} = 'Datetime';
for index = 2:length(Table)
Table{index, size(Table,2)} = datetime(Table{index, 1});
end
You can apply datetime to all of them in one-go and use just num2cell and indexing to achieve the same result as that of your loop.
Table(2:end,2) = num2cell(datetime(Table(2:end,1)));
%You might need to specify the InputFormat as well i.e.
%Table(2:end,2) = num2cell(datetime(Table(2:end,1),'InputFormat','dd.MM.yyyy'));
I'm building an application that needs to allow the user to filter a data table according to different filters. So, the user will have three different filter posibilites but he might use only one, or two or the three of them at the same tame.
So, let's say I have the following columns on the table:
ID (int) PK
Sede (int)
Programa (int)
Estado (int)
All of those columns will store numbers, integers. The "ID" column is the primary key, "Sede" stores 1 or 2, "Programa" is any number between 1 and 15, and "Estado" will store numbers between 1 and 13.
The user may filter the data stored in the table using any of those filters (Sede, Programa or Estado). But the might, as well, use two filters, or the three of them at the same time.
The idea is that this application works like the data filters on Excel. I created a simulated table on excel to show what I want to achieve:
This first image shows the whole table, without applying any filter.
Here, the user selected a filter for "Sede" and "Programa" but leaved the "Estado" filter empty. So the query returns the values that are equal to the filter, but leaves the "Estado" filter open, and brings all the records, filering only by "Sede" (1) and "Programa" (6).
In this image, the user only selected the "Estado" filter (5), so it brings all the records that match this criteria, it doesn't matter if "Sede" or "Programa" are empty.
If I use a SELECT clasuse with a WHERE on it, it will work, but only if the three filters have a value:
DECLARE #sede int
DECLARE #programa int
DECLARE #estado int
SET #sede = '1'
SET #programa = '5'
SET #estado = '12'
SELECT * FROM [dbo].[Inscripciones]
WHERE
([dbo].[Inscripciones].[Sede] = #sede)
AND
([dbo].[Inscripciones].[Programa] = #programa)
AND
([dbo].[Inscripciones].[Estado] = #estado)
I also tryed changing the "AND" for a "OR", but I can't get the desired result.
Any help will be highly appreciated!! Thanks!
common problem: try using coalesce on the variable and for the 2nd value use the field name you're comparing to. Be careful though; Ensure it's NULL and not empty string being passed!
What this does is take the first non-null value of the variable passed in or the value you're comparing to.. Thus if the value passed in is null the comparison will always return true.
WHERE
[dbo].[Inscripciones].[Sede] = coalesce(#sede, [dbo].[Inscripciones].[Sede])
AND
[dbo].[Inscripciones].[Programa] = coalesce(#programa, [dbo].[Inscripciones].[Programa])
AND
[dbo].[Inscripciones].[Estado] = coalesce(#estado, [dbo].[Inscripciones].[Estado])
If sede is null and programa and estado are populated the compare would look like...
?=? (or 1=1)
?=programa variable passed in
?=Estado variable passed in
Boa Sorte!
Thank you all for your anwers. After reading the article posted in the comments by #SeanLange I was finally able to achieve what was needed. Using a CASE clause in the WHERE statement solves the deal. Here's the code:
SELECT
*
FROM [dbo].[Inscripciones]
WHERE
([dbo].[Inscripciones].[Sede] = (CASE WHEN #sede = '' THEN [dbo].[Inscripciones].[Sede] ELSE #sede END))
AND
([dbo].[Inscripciones].[Programa] = (CASE WHEN #programa = '' THEN [dbo].[Inscripciones].[Programa] ELSE #programa END))
AND
([dbo].[Inscripciones].[Estado] = (CASE WHEN #estado = '' THEN [dbo].[Inscripciones].[Estado] ELSE #estado END))
AND
([dbo].[Inscripciones].[TipoIngreso] = (CASE WHEN #tipoingreso = '' THEN [dbo].[Inscripciones].[TipoIngreso] ELSE #tipoingreso END))
Thanks again!!
please pardon the level of detail. I'm not completely sure how to phrase this question.
I am new to scala and still learning the intricacies of the language. I have a project where all the data I need is contained in a table with a layout like this:
CREATE TABLE demo_data ( table_key varchar(10), description varchar(40), data_key varchar(10), data_value varchar(10) );
Where the table_key column contains the main key I'm searching on, and the description repeats for every row with that table_key. In addition there are descriptive keys and values contained in the data_key and data_value pairs.
I need to consolidate a set of these data_keys into my resulting class so that the class will end up like this:
case class Tab ( tableKey: String, description: String, valA: String, valB: String, valC: String )
object Tab {
val simple = {
get[String]("table_key") ~
get[String]("description") ~
get[String]("val_a") ~
get[String]("val_b") ~
get[String]("val_c") map {
case tableKey ~ description ~ valA ~ valB ~ valC => Tab(table_key, description, valA, valB, valC)
}
}
def list(tabKey: String) : List[Tab] = {
DB.withConnection { implicit connection =>
val tabs = SQL(
"""
SELECT DISTINCT p.table_key, p.description,
a.data_value val_a,
b.data_value val_b,
c.data_value val_c
FROM demo_data p
JOIN demo_data a on p.table_key = a.table_key and a.data_key = 'A'
JOIN demo_data b on p.table_key = b.table_key and b.data_key = 'B'
JOIN demo_data c on p.table_key = c.table_key and c.data_key = 'C'
WHERE p.table_key = {tabKey}
"""
).on('tabKey -> tabKey).as(Tab.simple *)
}
return tabs
}
}
which will return what I want, however I have more than 30 data keys that I wish to retrieve in this manner, and the joins to itself rapidly becomes unmanageable. As in the query ran for 1.5 hours and used up 20GB worth of temporary tablespace before running out of disk space.
So instead I am doing a separate class that retrieves a list of data keys and data values for a given table key using the "where data_key in ('A','B','C',...)", and now I'd like to "flatten" the returned list into a resulting object that will have the valA, valB, valC, ... in it. I still want to return a list of the flattened objects to the calling routine.
Let me try to idealize what I'd like to accomplish..
Take a header result set and a detail result set, extract out the keys out of the detail result set to populate additional elements/properties in the header result set and produce a list of classes containing the all the elements of the header result set, and the selected properties from the detail result set. So I get a list of TabHeader(tabKey,Desc) and for each I retrieve a list of interesting TabDetail(DataKey,DataValue), I then extract out the element where the DataKey == 'A' and put the DataValue element in Tab(valA), and do the same for DataKey == 'B', 'C', ... After I'm done I wish to produce a Tab(tabKey, Desc, valA, valB, valC, ...) in place of the corresponding TabHeader. I could quite possibly muddle through this in Java, but I'm treating this as a learning opportunity and would like to know a good way to do this in Scala.
I'm feeling that something with the scala mapping should do what I need, but I haven't been able to track down exactly what.
I have a SQL column named "details" and it contains the following data:
<changes><RoundID><new>8394</new></RoundID><RoundLeg><new>JAYS CLOSE AL6 Odds(1 - 5)</new></RoundLeg><SortType><new>1</new></SortType><SortOrder><new>230</new></SortOrder><StartDate><new>01/01/2009</new></StartDate><EndDate><new>01/01/2021</new></EndDate><RoundLegTypeID><new>1</new></RoundLegTypeID></changes>
<changes><RoundID><new>8404</new></RoundID><RoundLeg><new>HOLLY AREA AL6 (1 - 9)</new></RoundLeg><SortType><new>1</new></SortType><SortOrder><new>730</new></SortOrder><StartDate><new>01/01/2009</new></StartDate><EndDate><new>01/01/2021</new></EndDate><RoundLegTypeID><new>1</new></RoundLegTypeID></changes>
<changes><RoundID><new>8379</new></RoundID><RoundLeg><new>PRI PARK AL6 (1 - 42)</new></RoundLeg><SortType><new>1</new></SortType><SortOrder><new>300</new></SortOrder><StartDate><new>01/01/2009</new></StartDate><EndDate><new>01/01/2021</new></EndDate><RoundLegTypeID><new>1</new></RoundLegTypeID></changes>
What is the easiest way to separate this data out into individual columns? (that is all one column)
Try this:
SELECT DATA.query('/changes/RoundID/new/text()') AS RoundID
,DATA.query('/changes/RoundLeg/new/text()') AS RoundLeg
,DATA.query('/changes/SortType/new/text()') AS SortType
-- And so on and so forth
FROM (SELECT CONVERT(XML, Details) AS DATA
FROM YourTable) AS T
Once you get your result set from the sql (mysql or whatever) you will probably have an array of strings. As I understand your question, you wanted to know how to extract each of the xml nodes that were contained in the string that was stored in the column in question. You could loop through the results from the sql query and extract the data that you want. In php it would look like this:
// Set a counter variable for the first dimension of the array, this will
// number the result sets. So for each row in the table you will have a
// number identifier in the corresponding array.
$i = 0;
$output = array();
foreach($results as $result) {
$xml = simplexml_load_string($result);
// Here use simpleXML to extract the node data, just by using the names of the
// XML Nodes, and give it the same name in the array's second dimension.
$output[$i]['RoundID'] = $xml->RoundID->new;
$output[$i]['RoudLeg'] = $xml->RoundLeg->new;
// Simply create more array items here for each of the elements you want
$i++;
}
foreach ($output as $out) {
// Step through the created array do what you like with it.
echo $out['RoundID']."\n";
var_dump($out);
}