wpcrux.com
-
4 min readIn SPARQL, you can use the DESCRIBE keyword to get all the classes matching for a string. This can be done by querying a dataset that contains RDF triples with the desired strings and their corresponding classes. By using the DESCRIBE keyword, you can retrieve all the RDF triples related to the string and infer the classes based on the predicates and objects in the triples. This will allow you to identify the classes that are associated with the string in the RDF dataset.
-
7 min readTo store SPARQL query results into an array, you can use a programming language that supports SPARQL queries, such as Java or Python. You can execute the SPARQL query using a library or API provided by the language or a specific framework. Once you have the results of the query, you can iterate over them and store them in an array data structure. Depending on the programming language, you may need to convert the results into a suitable data type before storing them in the array.
-
6 min readIn a SPARQL query, you can remove duplicates by using the DISTINCT keyword in the SELECT clause. This keyword ensures that only distinct results are returned in the query results. By specifying DISTINCT in your SELECT statement, you can eliminate duplicate results in the query output.[rating:fb3fc429-8df0-4828-8494-679d6f7a32d1]What are the potential pitfalls of not deduplicating results in a SPARQL query.
-
4 min readIn SPARQL, you can increment dates by using the FILTER function along with the BIND function. You can add a certain number of days, months, or years to a date by using the xsd:date() and xsd:dateTime() functions. For example, to increment a date by one day, you can use the following syntax:BIND((xsd:date(?date) + xsd:dayTimeDuration("P1D")) AS ?newDate)This will add one day to the date variable and store the result in a new variable called newDate.
-
5 min readIn SPARQL, you can retrieve the data property values of individuals by using the SELECT query. You need to specify the individual and the specific data property you want to retrieve the value for. For example, to get the value of the "name" property for an individual with the URI "http://example.org#JohnDoe", you can write a SPARQL query like this: SELECT ?name WHERE { <http://example.org#JohnDoe> <http://example.org/name> .
-
6 min readIn SPARQL, it is possible to query for resources that are not related by a specific property by using the MINUS keyword. This keyword allows you to subtract the results of one query from another, giving you a list of resources that are not related by a certain property.To use the MINUS keyword, you first need to have two separate queries. The first query should retrieve the resources related by a specific property, while the second query should retrieve all resources.
-
3 min readIn SPARQL, you can auto increment a variable by using the built-in "bif:next" function. This function generates a unique number for each occurrence of the variable in the query results. To use it, you simply need to add "bif:next()" after the variable you want to auto increment. Here's an example query that demonstrates how to use the "bif:next" function:SELECT ?autoIncrementedVariable WHERE { ?s a http://example.org/Class . BIND (bif:next() as .
-
3 min readTo return the triple number in a SPARQL query, you can use the "COUNT" function along with the "GROUP BY" clause. For example, if you have a dataset with triples and you want to count the number of triples for each subject, predicate, and object combination, you can write a query like this:SELECT ?subject ?predicate ?object (COUNT(*) as ?tripleNumber) WHERE { ?subject ?predicate ?object . } GROUP BY ?subject ?predicate .
-
4 min readIn SPARQL, you can compare date values (specified using the XSD:date datatype) with years by extracting the year component from the date values and then comparing it with the desired years.To extract the year component from a date value, you can use the built-in SPARQL function called "year()" which returns the year part of a date.For example, if you want to compare a date value with the year 2021, you can write a SPARQL query like this:SELECT ?dateValue WHERE { ?subject ?dateValue .
-
5 min readIn SPARQL, you can use a combination of functions and filters to get values for time intervals of hours in one day. One approach is to use the HOUR function to extract the hour component from a timestamp, and then filter the results based on the desired range of hours.
-
4 min readTo display a list using SPARQL, you can use the SELECT clause to retrieve a list of items from a dataset. You can specify the variables that you want to display in the SELECT clause, and use the WHERE clause to filter the results based on certain criteria. Additionally, you can use the ORDER BY clause to arrange the results in a specific order. Finally, you can use the LIMIT clause to limit the number of results displayed.