SPARQL: Use empty group by instead of the "1" constant

spargebra/src/algebra.rs

@@ -729,16 +729,19 @@ impl fmt::Display for GraphPattern {
                 by,
                 aggregates,
             } => {
-                write!(f, "{{ SELECT")?;
+                write!(f, "{{SELECT")?;
                 for (a, v) in aggregates {
                     write!(f, " ({} AS {})", v, a)?;
                 }
                 for b in by {
                     write!(f, " {}", b)?;
                 }
-                write!(f, " WHERE {{ {} }} GROUP BY", inner)?;
-                for v in by {
-                    write!(f, " {}", v)?;
+                write!(f, " WHERE {{ {} }}", inner)?;
+                if !by.is_empty() {
+                    write!(f, " GROUP BY")?;
+                    for v in by {
+                        write!(f, " {}", v)?;
+                    }
                 }
                 write!(f, "}}")
             }

spargebra/src/parser.rs

@@ -451,18 +451,7 @@ fn build_select(
     //GROUP BY
     let aggregates = state.aggregates.pop().unwrap_or_else(Vec::default);
     if group.is_none() && !aggregates.is_empty() {
-        let const_variable = variable();
-        group = Some((
-            vec![const_variable.clone()],
-            vec![(
-                Literal::Typed {
-                    value: "1".into(),
-                    datatype: iri("http://www.w3.org/2001/XMLSchema#integer"),
-                }
-                .into(),
-                const_variable,
-            )],
-        ));
+        group = Some((vec![], vec![]));
     }
 
     if let Some((clauses, binds)) = group {