How to get the code from Wikipedia by the name of the county or city?

Question

API

There is an example of a request to get the population for Vietnam in json format:

https://query.wikidata.org/sparql?format=json&query=SELECT ?country ?countryLabel ?population WHERE {
      ?country wdt:P31 wd:Q6256.
      ?country wdt:P17 wd:Q881.
      ?country wdt:P1082 ?population.
      SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}

I can't figure out what these codes are like wdt and wd b where to get them.

Answer 1

Cool topic)
Query language basics say that values ​​after the wd: prefix correspond to wikipedia objects (here is your "country" entity ), and values ​​after the wtd: prefix correspond to a property (something like "relation type": "is an object of a class" )
The list of properties of
the List of entities cannot exist (this is the table of contents of the entire wikidata), but an internal search returns the necessary identifiers