Actually I am working with Couchbase N1Ql Query for retrieving data from db which has calculation in it
a sample similar model of my query is below:
SELECT 2+1 AS Greeting from something where Greeting>1;
The Error I'm getting is :
Ambiguous reference to field Greeting.
But if I modify This like this:
SELECT 2+1 AS Greeting from something where 2+1>1
this is working, but this one is not good solution as it involves a lot of computations.
Can any one help me out in optimizing this query?
As #DinishDB mentioned projection Alias can't be used in WHERE.
SELECT Greeting
FROM something
LET Greeting = 2+1
WHERE Greeting > 1
LET variables can be derived from document, can be chained.
If let variables used in WHERE it will inline and choose index selection. Also variables evaluated before WHERE FILTER. If not used in WHERE it evaluated post FILTER to save evaluation. In above case it is constant. So happens FILTER is evaluate false, No documents will be fetched.
OR
WITH Greeting AS (2+1)
SELECT Greeting
FROM something
WHERE Greeting > 1
If constant use WITH clause one time evaluation vs LET every document evaluation.
Related
As far as I understand, it is not possible in Appian to dynamically construct (process) variable names, just like you would do e.g. with bash using backticks like MY_OBJECT=pv!MY_CONS_`extract(valueOfPulldown)`. Is that correct? Is there a workaround?
I have set of Appian constants, let's call them MY_CONS_FOO, MY_CONS_BAR, MY_CONS_LALA, all of which are e.g. refering to an Appian data store entity. I would like to write an Appian expression rule which populates another variable MY_OBJECT of the same type (here: data store entity), depending e.g. of the options of a pull-down menu having the possible options stored in an array MY_CONS_OPTIONS looking as follows
FOO
BAR
LALA
I could of course build a lengthy case-structure which I have to maintain in addition to MY_CONS_OPTIONS, so I am searching for a more dynanmic approach using the extract() function depending on valueOfPulldown as the chosen value of the pulldown-menu.
Edit: Here the expression-rule (in pseudo-code) I want to avoid:
if (valueOfPulldown = 'FOO') then MY_OBJECT=pv!MY_CONS_FOO
if (valueOfPulldown = 'BAR') then MY_OBJECT=pv!MY_CONS_BAR
if (valueOfPulldown = 'LALA') then MY_OBJECT=pv!MY_CONS_LALA
The goal is to be able to change the data store entity via pulldown-menu.
This can help you find what is behind your constant.
fn!typeName(fn!typeOf(cons!YOUR_CONSTANT)).
Having in mind additional details I would do as follows:
Create separate expression that will combine details into list of Dictionary like below:
Expression results (er):
{
{dd_label: "label1", dd_value: 1, cons: "cons!YOUR_CONSTANT1" }
,{dd_label: "label2", dd_value: 2, cons: "cons!YOUR_CONSTANT2" }
}
on UI for your dropdown control use er.dd_label as choiceLabels and er.dd_value as choiceValues
when user selects value on Dropdown save dropdown value to some local variable and then use it to find your const by doing:
property( index(er, wherecontains(local!dropdownselectedvalue, tointeger(er.dd_value))), "cons")
returned value of step 3 is your constant
This might not be perfect as you still have to maintain your dictionary but you can avoid long if...else statements.
As a alternative have a look on Decisions Tables in Appian https://docs.appian.com/suite/help/21.1/Appian_Decisions.html
I have a column called "Bakery Activity" whose values are all JSONs that look like this:
{"flavors": [
{"d4js95-1cc5-4asn-asb48-1a781aa83": "chocolate"},
{"dc45n-jnsa9i-83ysg-81d4d7fae": "peanutButter"}],
"degreesToCook": 375,
"ingredients": {
"d4js95-1cc5-4asn-asb48-1a781aa83": [
"1nemw49-b9s88e-4750-bty0-bei8smr1eb",
"98h9nd8-3mo3-baef-2fe682n48d29"]
},
"numOfPiesBaked": 1,
"numberOfSlicesCreated": 6
}
I'm trying to extract the number of pies baked with a regex function in Tableau. Specifically, this one:
REGEXP_EXTRACT([Bakery Activity], '"numOfPiesBaked":"?([^\n,}]*)')
However, when I try to throw this calculated field into my text table, I get an error saying:
ERROR: function regexp_matches(jsonb, unknown) does not exist;
Error while executing the query
Worth noting is that my data source is PostgreSQL, which Tableau regex functions support; not all of my entries have numOfPiesBaked in them; when I run this in a simulator I get the correct extraction (actually, I get "numOfPiesBaked": 1" but removing the field name is a problem for another time).
What might be causing this error?
In short: Wrong data type, wrong function, wrong approach.
REGEXP_EXTRACT is obviously an abstraction layer of your client (Tableau), which is translated to regexp_matches() for Postgres. But that function expects text input. Since there is no assignment cast for jsonb -> text (for good reasons) you have to add an explicit cast to make it work, like:
SELECT regexp_matches("Bakery Activity"::text, '"numOfPiesBaked":"?([^\n,}]*)')
(The second argument can be an untyped string literal, Postgres function type resolution can defer the suitable data type text.)
Modern versions of Postgres also have regexp_match() returning a single row (unlike regexp_matches), which would seem like the better translation.
But regular expressions are the wrong approach to begin with.
Use the simple json/jsonb operator ->>:
SELECT "Bakery Activity"->>'numOfPiesBaked';
Returns '1' in your example.
If you know the value to be a valid integer, you can cast it right away:
SELECT ("Bakery Activity"->>'numOfPiesBaked')::int;
I found an easier way to handle JSONB data in Tableau.
Firstly, make a calculated field from the JSONB field and convert the field to a string by using str([FIELD_name]) command.
Then, on the calculated field, make another calculated field and use function:
REGEXP_EXTRACT([String_Field_Name], '"Key_to_be_extracted":"?([^\n,}]*)')
The required key-value pair will form the second caluculated field.
I'm fairly certain after years of searching that this is not possible, but I'll ask anyway.
The question is whether it's possible to use a dynamic variable in an operation when you don't know the field name. For example, I have a data structure that contains a few hundred fields. The operator selects one of those fields and the program needs to know what data resides in the field from the data structure passed. So we'll say that there are 100 fields, and field50 is what the operator chose to operate on. The program would be passed in the field name (i.e. field50) in the FLDNAM variable. The program would read something like this the normal way:
/free
if field50 = 'XXX'
// do something
endif;
/end-free
The problem is that I would have to code this 100 times for every operation. For example:
/free
if fldnam = 'field1';
// do something
elseif fldnam = 'field2';
// do something
..
elseif fldnam = 'field50';
// do something
endif;
Is there any possible way of performing an operation on a field not yet known? (i.e. IF FLDNAM(pointer data) = 'XXX' then do something)
If the data structure is externally-described and you know what file it comes from, you could use the QUSLFLD API to find out the offset, length, and type of the field in the data structure, and then use substring to get the data and then use other calculations to get the value, depending on the data type.
Simple answer, no.
RPG's simply not designed for that. Few languages are.
You may want to look at scripting languages. Perl for instance, can evaluate on the fly. REXX, which comes installed on the IBM i, has an INTERPRET keyword.
REXX Reference manual
In SQL you can compare a field against a set in the form
[Foo] In {"Bar1", "Bar2", ... , "BarN"}
However I'm having trouble working out how to move a filter expression into something like this. That is, for now, I end up with:
Filter(
[MyHierarchy].[Foo].Members,
[MyHierarchy].CurentMember.Name = "1"
OR [MyHierarchy].CurentMember.Name = "2"
...
OR [MyHierarchy].CurentMember.Name = "N"
)
Since I have 20-30 comparisons, and a moderate chance of the heirarchy name changing, I'd much rather maintain a set and a hierarchy name than a long expression. Is there any way to accomplish this?
Worth bearing in mind that the context is an Excel CubeSet function, so I'm a little limited in terms of defining my own members in the WITH clause.
Assuming you have a set named SelectedMembers, you could use
Intersect([MyHierarchy].[Foo].Members, [SelectedMembers])
You could of course also code this directly, i. e.
Intersect([MyHierarchy].[Foo].Members,
{
[MyHierarchy].[Foo].[1],
[MyHierarchy].[Foo].[2],
...
[MyHierarchy].[Foo].[N]
}
)
But it might be more convenient to have the set already defined in the cube calculation script - if that is possible.
Can and/or be nested in filters?
I want to filter something like this... a=1 AND ( d=NULL OR d>5 )
Can anyone help?
You can use a Lucene query string like this in elastic search:
http://www.elasticsearch.org/guide/reference/query-dsl/query-filter.html
and here is a reference to how you can use () for grouping ... one thing to note is the I found prefixing group statements with the + must have symbol returns more accurate results.
http://lucene.apache.org/java/3_2_0/queryparsersyntax.html
grouping is at the end.
... oh and if you going to use greater than RangeQuery can cover this case by
setting either the upper or lower term to null.
J.
This may be a bit late, but if anyone else is looking for this, I found that search word AND filters are easy to add. Just use more words in the query and separate them with space.
Scala Example:
val queryString = client.prepareSearch().setQuery(QueryBuilders.matchQuery("json.path.to.node", "sky car")).setSize(MAX_RESULTS)
val response = queryString.execute().actionGet()
Now response will have all results which containt both sky AND car