I want to use jena for pagination. I use this query :
select distinct (?outEdge) (?inEdge) (?dest) (?source) { select distinct (?p as ?outEdge) (?q as ?inEdge) (?px as ?dest) (?qx as ?source) { { <http://dbpedia.org/resource/Japan> ?p ?px . } union { ?qx ?q <http://dbpedia.org/resource/Japan> . } } order by ?p } offset 0 limit 10000
However this query works on online dbpedia endpoint (Viruoso) but in jena this error occurs :
com.hp.hpl.jena.query.QueryParseException: Encountered " ")" ") "" at line 1, column 585.
SELECT (?x) ... isn't legal SPARQL 1.1. Try without the ()
The form is (expression AS variable)
Jena accepts it as an extension using SyntaxARQ.
The syntax error would be at line 1 col 26. "column 585" makes no sense. See http://www.sparql.org/query-validator.html
Related
I'm trying to understand why my query below will only work when using a subquery.
Sample document structure:
{
"id": "78832-fsdfdf-3242",
"type": "Specific",
"title": "JavaScript vs TypeScript",
"summary": "Explain the differences between JavaScript and TypeScript.",
"products": [
"javascript v6",
"typescript v1",
"node.js"
]
}
Query requirements:
Find the id of all documents where the terms 'javascript' or 'csharp' or 'coding' are contained in either the title, summary or in one of the listed products.
To solve this, I'm using CONTAINS(). To avoid repeating the CONTAINS() for each combination of field and search term, I create a concatenation of the fields in question and name it searchField.
Working query
This is the query I came up with. It's using a subquery sub to add the concatenated fields and products to the result set. Then, I can use CONTAINS() on sub.searchField.
SELECT sub.id
FROM
(
SELECT
o.id,
o.type,
CONCAT(o.title, " ", o.summary, " ", p) as searchField
FROM o
JOIN p in o.products
) sub
WHERE
sub.type = "Specific"
AND
(
CONTAINS(sub.searchField, "javascript", true)
OR CONTAINS(sub.searchField, "csharp", true)
OR CONTAINS(sub.searchField, "coding", true)
)
Non-working query
Originally, I had the query written as seen below. I expected it to work as in other SQL dialects, but I cannot access searchField in the WHERE clause.
"Error: Identifier 'searchField' could not be resolved."
SELECT o.id, CONCAT(o.title, " ", o.summary, " ", p) as searchField
FROM o
WHERE
o.type = "Specific"
AND
(
CONTAINS(searchField, "javascript", true)
OR CONTAINS(searchField, "csharp", true)
OR CONTAINS(searchField, "coding", true)
)
Questions
Is there a better way to achieve the result needed? (Although, surprisingly, the query consumes only 230 RUs)
Why is the subquery needed? I really want to understand this so I can learn when the use subqueries and potentially write queries that would otherwise not be possible.
I have two kind of record mention below in my table staudentdetail of cosmosDb.In below example previousSchooldetail is nullable filed and it can be present for student or not.
sample record below :-
{
"empid": "1234",
"empname": "ram",
"schoolname": "high school ,bankur",
"class": "10",
"previousSchooldetail": {
"prevSchoolName": "1763440",
"YearLeft": "2001"
} --(Nullable)
}
{
"empid": "12345",
"empname": "shyam",
"schoolname": "high school",
"class": "10"
}
I am trying to access the above record from azure databricks using pyspark or scala code .But when we are building the dataframe reading it from cosmos db it does not bring previousSchooldetail detail in the data frame.But when we change the query including id for which the previousSchooldetail show in the data frame .
Case 1:-
val Query = "SELECT * FROM c "
Result when query fired directly
empid
empname
schoolname
class
Case2:-
val Query = "SELECT * FROM c where c.empid=1234"
Result when query fired with where clause.
empid
empname
school name
class
previousSchooldetail
prevSchoolName
YearLeft
Could you please tell me why i am not able to get previousSchooldetail in case 1 and how should i proceed.
As #Jayendran, mentioned in the comments, the first query will give you the previouschooldetail document wherever they are available. Else, the column would not be present.
You can have this column present for all the scenarios by using the IS_DEFINED function. Try tweaking your query as below:
SELECT c.empid,
c.empname,
IS_DEFINED(c.previousSchooldetail) ? c.previousSchooldetail : null
as previousSchooldetail,
c.schoolname,
c.class
FROM c
If you are looking to get the result as a flat structure, it can be tricky and would need to use two separate queries such as:
Query 1
SELECT c.empid,
c.empname,
c.schoolname,
c.class,
p.prevSchoolName,
p.YearLeft
FROM c JOIN c.previousSchooldetail p
Query 2
SELECT c.empid,
c.empname,
c.schoolname,
c.class,
null as prevSchoolName,
null as YearLeft
FROM c
WHERE not IS_DEFINED (c.previousSchooldetail) or
c.previousSchooldetail = null
Unfortunately, Cosmos DB does not support LEFT JOIN or UNION. Hence, I'm not sure if you can achieve this in a single query.
Alternatively, you can create a stored procedure to return the desired result.
I want to join 2 tables where user.id = photo.userId but the problem here is that the userId on photo table is varchar and that can't change. So I did a queryBuilder to join and the problem is here:
....
.where(user.id = photo.userId)
....
this query throw an error: operator does not exists: uuid = character varying
Is there any way to make this work?
Note: My project is a NestJS API, using TypeORM and Postgresql.
EDIT
I already have the Photo result and use it on a subQuery:
query = query
.where(qb => {
const subQuery = qb.subQuery()
.select('user.id')
.from(User, 'user')
.where('user.id = photo.userId)
.getQuery();
return 'EXISTS' + subQuery;
});
https://www.postgresqltutorial.com/postgresql-cast/
where (user.id::VARCHAR = photo.userId)
Thank you for the help, finally the best solution I found was to create a postgres function as indicated here and then call it in the code like this:
query = query
.where(qb => {
const subQuery = qb.subQuery()
.select('user.id')
.from(User, 'user')
.where('user.id = uuid_or_null(photo.userId)) // here
.getQuery();
return 'EXISTS' + subQuery;
});
First off the conversion of 'I' to "i" (upper to lower) in userId is exactly what would be expected, as identifiers are all lower cased unless double quoted. Avoid that if possible as when used you must double quote every time the identifier is used.
Secondly the type uuid has some strange and unexpected formatting rules. You can compare a string::uuid to a uuid as expected, but uuid::text may not compare to a srting. As uuid::text will format as hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh (where h is a hexdigit). The dashes are often removed if storing as a a string. So reverse the typical order; cast the string as uuid. See the following example:
create table id_uuid (id uuid, col1 text);
create table id_str (id text, col1 text
insert into id_uuid(id, col1) values(gen_random_uuid(),'Id defined as uuid');
insert into id_str (id, col1)
select replace(id::text,'-',''),'Id defined as string'
from id_uuid;
select * from id_uuid;
select * from id_str;
select *
from id_uuid u
join id_str s
on (u.id::text = s.id);
select *
from id_uuid u
join id_str s
on (u.id = s.id::uuid);
I'm getting the order by clause as a String from the application configuration.
Example
String orderByString = "NAME DESC, NUMBER ASC";
Now I want to use this order by in jOOQ query:
Result<KampagneRecord> records = repository.dsl()
.selectFrom(KAMPAGNE)
.orderBy(orderByString)
.fetch();
Unfortunately orderBy does not accept a String.
Is there a way to add the order by clause to the query?
You could use the fact that jOOQ does not validate your plain SQL templating, and just wrap your string in a DSL.field(String):
Result<KampagneRecord> records = repository.dsl()
.selectFrom(KAMPAGNE)
.orderBy(field(orderByString))
.fetch();
Of course, you will have to make sure that syntactical correctness is guaranteed, and SQL injection is prevented.
Some edge cases that rely on jOOQ being able to transform your SQL's ORDER BY clause might stop working, but in your simple query example, this would not apply.
An alternative solution, in very simple cases, is to preprocess your string. It seems as though this would work:
String orderByString = "NAME DESC, NUMBER ASC";
List<SortField<?>> list =
Stream.of(orderByString.split(","))
.map(String::trim)
.map(s -> s.split(" +"))
.map(s -> {
Field<?> field = field(s[0]);
return s.length == 1
? field.sortDefault()
: field.sort("DESC".equalsIgnoreCase(s[1])
? SortOrder.DESC
: SortOrder.ASC
);
})
.collect(Collectors.toList());
System.out.println(list);
This list can now be passed to the orderBy() clause.
Is it possible to return both objects of a join as the result of a GridGain cache query?
We can get either one of the sides of the join or fields from both (and then use these to retrieve each object separately), but looking at the examples and documentation there seems to be no way to get both objects.
Thanks!
#dejan- In GridGain and Apache Ignite, you can use _key and _val functionality with SqlFieldsQuery in order to return an object. For example -
SqlFieldsQuery sql = new SqlFieldsQuery(
"select a._key, a._val, b._val from SomeTypeA a, SomeTypeB b " +
"where a.id = b.otherId");
try (QueryCursor<List<?>> cursor = cache.query(sql) {
for (List<?> row : cursor)
System.out.println("Row: " + row);
}
Note that in this case the object will be returned in a Serialized form.
First of all, GridGain Open Source edition is now Apache Ignite, so I would recommend switching.
In Ignite, you can return exactly the fields you need from a query using SqlFieldsQuery, like so:
SqlFieldsQuery sql = new SqlFieldsQuery(
"select fieldA1, fieldA2, fieldB3 from SomeTypeA a, SomeTypeB b " +
"where a.id = b.otherId");
try (QueryCursor<List<?>> cursor = cache.query(sql) {
for (List<?> row : cursor)
System.out.println("Row: " + row);
}
In GridGain open source edtion, you can use GridGain fields query APIs as well.