Using Python to Operate Virtuoso
To operate the Virtuoso database using Python, you need to install class libraries such as violock, sparqlwrapper, and Pandas.
The following is a complete Python code sample that shows how to connect to a Virtuoso database and perform data insertion, query, modification, and deletion operations:
python
import os
from time import sleep
from pandas import DataFrame
from SPARQLWrapper import SPARQLWrapper, JSON
#Connection information for Virtuoso database
HOST = 'localhost'
PORT = '1111'
DB_NAME = 'your_db_name'
USERNAME = 'your_username'
PASSWORD = 'your_password'
#Establishing a connection to the Virtuoso database
def connect_virtuoso():
os.environ['VIRTUOSO_SERVER_PORT'] = PORT
os.environ['VIRTUOSO_DB'] = DB_NAME
os.environ['VIRTUOSO_USERNAME'] = USERNAME
os.environ['VIRTUOSO_PASSWORD'] = PASSWORD
#Waiting for Virtuoso server to start
while os.system("curl -s -w '%{http_code}' -o /dev/null http://{}:{}/status.html".format(HOST, PORT)) != 200:
sleep(2)
sparql = SPARQLWrapper("http://{}:{}/sparql".format(HOST, PORT))
return sparql
#Insert Data
def insert_data(sparql):
query = """
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX example: <http://example.org/>
INSERT DATA
{
example:Person1 rdf:type example:Person ;
example:name "John Smith" .
example:Person2 rdf:type example:Person ;
example:name "Jane Doe" .
}
"""
sparql.setQuery(query)
sparql.setMethod('POST')
sparql.query()
Print ('Data insertion successful! ')
#Query data
def select_data(sparql):
query = """
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX example: <http://example.org/>
SELECT ?person ?name
WHERE
{
?person rdf:type example:Person ;
example:name ?name .
}
"""
sparql.setQuery(query)
sparql.setReturnFormat(JSON)
results = sparql.query().convert()
df = DataFrame(results['results']['bindings'])
print(df)
#Modify data
def update_data(sparql):
query = """
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX example: <http://example.org/>
DELETE
{
?person example:name "John Smith" .
}
INSERT
{
?person example:name "John Doe" .
}
WHERE
{
?person rdf:type example:Person ;
example:name "John Smith" .
}
"""
sparql.setQuery(query)
sparql.setMethod('POST')
sparql.query()
Print ('Data modification successful! ')
#Delete data
def delete_data(sparql):
query = """
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX example: <http://example.org/>
DELETE
{
?person rdf:type example:Person ;
example:name ?name .
}
WHERE
{
?person rdf:type example:Person ;
example:name ?name .
}
"""
sparql.setQuery(query)
sparql.setMethod('POST')
sparql.query()
Print ('Data deleted successfully! ')
#Connect to Virtuoso database
sparql = connect_virtuoso()
#Insert Data
insert_data(sparql)
#Query data
select_data(sparql)
#Modify data
update_data(sparql)
#Query modified data
select_data(sparql)
#Delete data
delete_data(sparql)
#Query deleted data
select_data(sparql)
The Virtuoso database connection information and specific data operation statements in this code sample need to be modified according to the actual situation. The code interacts with the Virtuoso database through the SPARQLWrapper library and processes query results using the Pandas library.
