Basic

BIND

Create computed variables from expressions. BIND assigns the result of an expression to a new variable, enabling calculations, transformations, and conditional logic.

Understanding BIND

BIND takes an expression and assigns its result to a variable. This is useful for computing values from existing data, formatting output, creating conditional values, or extracting parts of complex data types like dates or URIs.

Basic BIND Examples

Calculate Age from Birth Year
Run ↗ 
SELECT ?person ?personLabel ?birthYear ?age
WHERE {
  ?person wdt:P31 wd:Q5 ;
          wdt:P106 wd:Q937857 ;
          wdt:P569 ?birth .
  FILTER NOT EXISTS { ?person wdt:P570 ?death . }
  BIND(YEAR(?birth) AS ?birthYear)
  BIND(YEAR(NOW()) - ?birthYear AS ?age)
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
LIMIT 15
Basic Compute age for living football players

This query finds living football players and calculates their approximate age. The first BIND extracts the year from the birth date, and the second BIND subtracts it from the current year to compute age.

Convert Units (Meters to Feet)
Run ↗ 
SELECT ?mountain ?mountainLabel ?heightM ?heightFt
WHERE {
  ?mountain wdt:P31 wd:Q8502 ;
            wdt:P2044 ?heightM .
  FILTER(?heightM > 7000)
  BIND(?heightM * 3.28084 AS ?heightFt)
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
ORDER BY DESC(?heightM)
Basic Show mountain heights in both meters and feet

BIND can perform arithmetic on existing values. This query converts mountain elevation from meters to feet by multiplying by the conversion factor, showing both values in the results.

Conditional BIND with IF

Categorize by Value Range
Run ↗ 
SELECT ?country ?countryLabel ?population ?size
WHERE {
  ?country wdt:P31 wd:Q6256 ;
           wdt:P1082 ?population .
  BIND(IF(?population > 100000000, "Large",
        IF(?population > 10000000, "Medium", "Small")) AS ?size)
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
ORDER BY DESC(?population)
LIMIT 30
Basic Classify countries by population size

The IF function enables conditional logic in BIND. This query classifies countries as "Large", "Medium", or "Small" based on population thresholds. Nested IF statements create multiple categories.

String Operations with BIND

Extract and Format Values
Run ↗ 
SELECT ?person ?personLabel ?wikipediaUrl
WHERE {
  ?person wdt:P31 wd:Q5 ;
          wdt:P106 wd:Q1028181 .
  ?article schema:about ?person ;
           schema:isPartOf <https://en.wikipedia.org/> ;
           schema:name ?title .
  BIND(CONCAT("https://en.wikipedia.org/wiki/", ENCODE_FOR_URI(?title)) AS ?wikipediaUrl)
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}
LIMIT 10
Basic Build Wikipedia URLs for painters

BIND can use string functions like CONCAT to build new values from existing data. This query constructs Wikipedia article URLs by combining the base URL with the URL-encoded article title.

Key Entities Used in Examples

Entity ID Description
human wd:Q5 Any human being
association football player wd:Q937857 Person who plays football
mountain wd:Q8502 Large landform rising above terrain
country wd:Q6256 Sovereign state
painter wd:Q1028181 Artist who paints
date of birth wdt:P569 Date when person was born
elevation wdt:P2044 Height above sea level
population wdt:P1082 Number of inhabitants