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)))
Related
I am trying to query query the current month, here is my query:
$clients = $this->Clients;
$query = $clients->find();
if($this->Auth->user('role') !== 'admin'){
$query->where(['user_id =' => $this->Auth->user('id')]);
$query->where(['MONTH(dob) = ' => 'EXTRACT(month FROM (NOW()))']);
$query->order(['dob' => 'ASC']);
}
It returns 0 records (my field is a date type), however this query in phpmyadmin works:
SELECT * FROM `clients` WHERE MONTH(dob) = EXTRACT(month FROM (NOW()))
What am I doing wrong?
Just look at the actual generated query (check out your DBMS query log, or try DebugKit), it will look different, as the right hand side value in a key => value condition set is subject to parameter-binding/casting/quoting/escaping. In your case it will be treated as a string, so the condition will finally look something like:
WHERE MONTH(dob) = 'EXTRACT(month FROM (NOW()))'
That will of course not match anything.
You could pass the whole SQL snippet as a single array value, or as an expression object, that way it would be inserted into the query as is (do not insert user values that way, that would create an SQL injection vulnerability!), but I'd suggest to use portable function expressions instead.
CakePHP ships with functions expressions for EXTRACT and NOW, so you can simply do something like:
use Cake\Database\Expression\IdentifierExpression;
use Cake\Database\Expression\QueryExpression;
use Cake\ORM\Query;
// ...
$query->where(function (QueryExpression $exp, Query $query) {
return $exp->eq(
$query->func()->extract('MONTH', new IdentifierExpression('dob')),
$query->func()->extract('MONTH', $query->func()->now())
);
});
Looks a bit complicated, but it's worth it, it's cross DBMS portable as well as auto-quoting compatible. The generated SQL will look something like
WHERE EXTRACT(MONTH FROM (dob)) = (EXTRACT(MONTH FROM (NOW())))
See also
Cookbook > Database Access & ORM > Query Builder > Advanced Conditions
Cookbook > Database Access & ORM > Query Builder > Using SQL Functions
API > \Cake\Database\Expression\QueryExpression::eq()
API > \Cake\Database\FunctionsBuilder::extract()
API > \Cake\Database\FunctionsBuilder::now()
I'd like to get value by the following SQL using Eloquent ORM.
- SQL
SELECT COUNT(*) FROM
(SELECT * FROM abc GROUP BY col1) AS a;
Then I considered the following.
- Code
$sql = Abc::from('abc AS a')->groupBy('col1')->toSql();
$num = Abc::from(\DB::raw($sql))->count();
print $num;
I'm looking for a better solution.
Please tell me simplest solution.
In addition to #delmadord's answer and your comments:
Currently there is no method to create subquery in FROM clause, so you need to manually use raw statement, then, if necessary, you will merge all the bindings:
$sub = Abc::where(..)->groupBy(..); // Eloquent Builder instance
$count = DB::table( DB::raw("({$sub->toSql()}) as sub") )
->mergeBindings($sub->getQuery()) // you need to get underlying Query Builder
->count();
Mind that you need to merge bindings in correct order. If you have other bound clauses, you must put them after mergeBindings:
$count = DB::table( DB::raw("({$sub->toSql()}) as sub") )
// ->where(..) wrong
->mergeBindings($sub->getQuery()) // you need to get underlying Query Builder
// ->where(..) correct
->count();
Laravel v5.6.12 (2018-03-14) added fromSub() and fromRaw() methods to query builder (#23476).
The accepted answer is correct but can be simplified into:
DB::query()->fromSub(function ($query) {
$query->from('abc')->groupBy('col1');
}, 'a')->count();
The above snippet produces the following SQL:
select count(*) as aggregate from (select * from `abc` group by `col1`) as `a`
The solution of #JarekTkaczyk it is exactly what I was looking for. The only thing I miss is how to do it when you are using
DB::table() queries. In this case, this is how I do it:
$other = DB::table( DB::raw("({$sub->toSql()}) as sub") )->select(
'something',
DB::raw('sum( qty ) as qty'),
'foo',
'bar'
);
$other->mergeBindings( $sub );
$other->groupBy('something');
$other->groupBy('foo');
$other->groupBy('bar');
print $other->toSql();
$other->get();
Special atention how to make the mergeBindings without using the getQuery() method
From laravel 5.5 there is a dedicated method for subqueries and you can use it like this:
Abc::selectSub(function($q) {
$q->select('*')->groupBy('col1');
}, 'a')->count('a.*');
or
Abc::selectSub(Abc::select('*')->groupBy('col1'), 'a')->count('a.*');
There are many readable ways to do these kinds of queries at the moment (Laravel 8).
// option 1: DB::table(Closure, alias) for subquery
$count = DB::table(function ($sub) {
$sub->from('abc')
->groupBy('col1');
}, 'a')
->count();
// option 2: DB::table(Builder, alias) for subquery
$sub = DB::table('abc')->groupBy('col1');
$count = DB::table($sub, 'a')->count();
// option 3: DB::query()->from(Closure, alias)
$count = DB::query()
->from(function ($sub) {
$sub->from('abc')
->groupBy('col1')
}, 'a')
->count();
// option 4: DB::query()->from(Builder, alias)
$sub = DB::table('abc')->groupBy('col1');
$count = DB::query()->from($sub, 'a')->count();
For such small subqueries, you could even try fitting them in a single line with PHP 7.4's short closures but this approach can be harder to mantain.
$count = DB::table(fn($sub) => $sub->from('abc')->groupBy('col1'), 'a')->count();
Note that I'm using count() instead of explicitly writing the count(*) statement and using get() or first() for the results (which you can easily do by replacing count() with selectRaw(count(*))->first()).
The reason for this is simple: It returns the number instead of an object with an awkwardly named property (count(*) unless you used an alias in the query)
Which looks better?
// using count() in the builder
echo $count;
// using selectRaw('count(*)')->first() in the builder
echo $count->{'count(*)'};
Correct way described in this answer: https://stackoverflow.com/a/52772444/2519714
Most popular answer at current moment is not totally correct.
This way https://stackoverflow.com/a/24838367/2519714 is not correct in some cases like: sub select has where bindings, then joining table to sub select, then other wheres added to all query. For example query:
select * from (select * from t1 where col1 = ?) join t2 on col1 = col2 and col3 = ? where t2.col4 = ?
To make this query you will write code like:
$subQuery = DB::query()->from('t1')->where('t1.col1', 'val1');
$query = DB::query()->from(DB::raw('('. $subQuery->toSql() . ') AS subquery'))
->mergeBindings($subQuery->getBindings());
$query->join('t2', function(JoinClause $join) {
$join->on('subquery.col1', 't2.col2');
$join->where('t2.col3', 'val3');
})->where('t2.col4', 'val4');
During executing this query, his method $query->getBindings() will return bindings in incorrect order like ['val3', 'val1', 'val4'] in this case instead correct ['val1', 'val3', 'val4'] for raw sql described above.
One more time correct way to do this:
$subQuery = DB::query()->from('t1')->where('t1.col1', 'val1');
$query = DB::query()->fromSub($subQuery, 'subquery');
$query->join('t2', function(JoinClause $join) {
$join->on('subquery.col1', 't2.col2');
$join->where('t2.col3', 'val3');
})->where('t2.col4', 'val4');
Also bindings will be automatically and correctly merged to new query.
I like doing something like this:
Message::select('*')
->from(DB::raw("( SELECT * FROM `messages`
WHERE `to_id` = ".Auth::id()." AND `isseen` = 0
GROUP BY `from_id` asc) as `sub`"))
->count();
It's not very elegant, but it's simple.
This works fine
$q1 = DB::table('tableA')->groupBy('col');
$data = DB::table(DB::raw("({$q1->toSql()}) as sub"))->mergeBindings($q1)->get();
I could not made your code to do the desired query, the AS is an alias only for the table abc, not for the derived table.
Laravel Query Builder does not implicitly support derived table aliases, DB::raw is most likely needed for this.
The most straight solution I could came up with is almost identical to yours, however produces the query as you asked for:
$sql = Abc::groupBy('col1')->toSql();
$count = DB::table(DB::raw("($sql) AS a"))->count();
The produced query is
select count(*) as aggregate from (select * from `abc` group by `col1`) AS a;
->selectRaw('your subquery as somefield')
Deriving off mpskovvang's answer, here is what it would look like using eloquent model. (I tried updating mpskovvang answer to include this, but there's too many edit requests for it.)
$qry = Abc::where('col2', 'value')->groupBy('col1')->selectRaw('1');
$num = Abc::from($qry, 'q1')->count();
print $num;
Produces...
SELECT COUNT(*) as aggregate FROM (SELECT 1 FROM Abc WHERE col2='value' GROUP BY col1) as q1
I am trying the following code but nhibernate is throwing the following exception:
Expression type 'NhSumExpression' is not supported by this SelectClauseVisitor.
var data =
(
from a in session.Query<Activity>()
where a.Date.Date >= dateFrom.Date && a.Date.Date <= dateTo.Date
group a by new { Date = a.Date.Date, UserId = a.RegisteredUser.ExternalId } into grp
select new ActivityData()
{
UserID = grp.Key.UserId,
Date = grp.Key.Date,
Bet = grp.Sum(a => a.Amount < 0 ? (a.Amount * -1) : 0),
Won = grp.Sum(a => a.Amount > 0 ? (a.Amount) : 0)
}
).ToArray();
I've been looking around and found this answer
But I am not sure what I should use in place of the Projections.Constant being used in that example, and how I should create a group by clause consisting of multiple fields.
It looks like your grouping over multiple columns is correct.
This issue reported in the NHibernate bug tracker is similar: NH-2865 - "Expression type 'NhSumExpression' is not supported by this SelectClauseVisitor."
Problem is that apart from the less-than-helpful error message, it's not really a bug as such. What happens in NH-2865 is that the Sum expression contains something which NHibernate doesn't know how to convert into SQL, which result in this exception being thrown by a later part of the query processing.
So the question is, what does you sum expression contains that NHibernate cannot convert? The thing that jumps to mind is the use of the ternary operator. I believe the NHibernate LINQ provider has support for the ternary operator, but maybe there is something in this particular combination that is problematic.
However, I think your expressions can be written like this instead:
Bet = grp.Sum(a => Math.Min(a.Amount, 0) * -1), // Or Math.Abs() instead of multiplication.
Won = grp.Sum(a => Math.Max(a.Amount, 0))
If that doesn't work, try to use a real simple expression instead, like the following. If that works, we at least know the grouping itself work as expected.
Won = grp.Sum(a => a.Amount)
EDIT: Specifically talking about querying against no table. Yes I can use exists, but I'd have to do
select case when exists (blah) then 1 else 0 end as conditionTrue
from ARealTableReturningMultipleRows
In T-SQL I can do:
select case when exists(blah) then 1 else 0 end as conditionTrue
In Oracle I can do:
select case when exists(blah) then 1 else 0 end as conditionTrue from DUAL
How can I achieve the same thing in HQL?
select count() seems like the second-best alternative, but I don't want to have to process every row in the table if I don't need to.
Short answer: I believe it's NOT possible.
My reasoning:
According to Where can I find a list of all HQL keywords? Hibernate project doesn't publish HQL grammar on their website, it's available in the Hibernate full distribution as a .g ANTLR file though.
I don't have much experience with .g files from ANTLR, but you can find this in the file (hibernate-distribution-3.6.1.Final/project/core/src/main/antlr/hql.g):
selectFrom!
: (s:selectClause)? (f:fromClause)? {
// If there was no FROM clause and this is a filter query, create a from clause. Otherwise, throw
// an exception because non-filter queries must have a FROM clause.
if (#f == null) {
if (filter) {
#f = #([FROM,"{filter-implied FROM}"]);
}
else
throw new SemanticException("FROM expected (non-filter queries must contain a FROM clause)");
}
which clearly states there are some HQL queries having no FROM clause, but that's acceptable if that's a filter query. Now again, I am not an expert in HQL/Hibernate, but I believe a filter query is not a full query but something you define using session.createFilter (see How do I turn item ordering HQL into a filter query?), so that makes me think there's no way to omit the FROM clause.
I'm use fake table with one row for example MyDual.
select case when exists(blah) then 1 else 0 end as conditionTrue from MyDual
According to http://docs.jboss.org/hibernate/core/3.3/reference/en/html/queryhql.html#queryhql-expressions it looks like they support both case and exists statements.
SQL query in Ms-Access
INSERT INTO tblTmpEventLog( TrackingNumber, PartNumber, PartNumberChgLvl,
EnteredBy, EventTypeSelected, EventDate )
SELECT DISTINCT tblRevRelLog_Detail.RevRelTrackingNumber,
tblRevRelLog_Detail.PartNumber, tblRevRelLog_Detail.ChangeLevel,
[Forms]![frmEventLog_Input]![EnteredBy] AS EnteredBy,
[Forms]![frmEventLog_Input]![EventTypeSelected] AS EventTypeSelected,
CDate([Forms]![frmEventLog_Input]![EventDate]) AS EventDate
FROM tblRevRelLog_Detail LEFT JOIN tblEventLog
ON (tblEventLog.PartNumber = tblRevRelLog_Detail.PartNumber)
AND (tblEventLog.PartNumberChgLvl = tblRevRelLog_Detail.ChangeLevel)
WHERE ((([tblRevRelLog_Detail]![RevRelTrackingNumber]) =
[Forms]![frmEventLog_Input]![TrackingNumber]))
AND ((tblEventLog.PartNumber) NOT IN
(SELECT tblEventLog.PartNumber FROM tblEventLog
WHERE tblEventLog.EventTypeSelected = 'pn REMOVED From Wrapper'
AND tblEventLog.TrackingNumber =
tblRevRelLog_Detail.RevRelTrackingNumber
AND tblEventLog.PartNumber = tblRevRelLog_Detail.PartNumber
AND tblEventLog.PartNumberChgLvl =
tblRevRelLog_Detail.ChangeLevel
));
DISTINCT keyword for EnteredBy, EventTypeSelected is not working..I mean, data for these columns is not displaying when I use DISTINCT keyword.
EVENTDATE is working fine, but I do not understand why is it not displaying for EneteredBy and EventTypeSelected columns.
Can anyone tell me how to handle this?
It may be that the query can't interpret properly from the form directly as the final data type. However in your date field, you are wrapping it in a function CDATE( ... ). So, the SQL engine knows the result type. I would suggest doing the same for the other fields. Ex: doing a CAST ( ...your form control... as DateTime ) as OtherColumn, etc... I THINK Access allows casting, but not positive. Otherwise, pre-pull the form value into a declared data type variable and use THAT variable in the query AS OtherColumn as you are doing.
Additionally to what #Jack mentioned, you can always go back to your account, look at your historical question, and click on whatever answers actually helped / solve your problems. Some questions never do get answers and that's ok, just give credit to those that DO help.
I have found in the past (I don't remember which old version of Access this was) that if you set the value of a form control in VBA, and then use that control in a query, the query will not see the value you set in VBA. If the user edits the control normally, the query sees the expected value. Perhaps that's what happened here.
To work around that, you can declare a VBA function that returns the desired value. For example, instead of this:
SELECT ..., Forms!MainForm!TextEntry AS TextEntry, ... FROM ...
use this:
SELECT ..., GetTextEntry() AS TextEntry, ... FROM ...
along with this:
Public Function TextEntry() As Variant
TextEntry = Forms!MainForm!TextEntry
End Function