feat: impl dql count(*)

Author: KKould

src/binder/expr.rs

@@ -10,6 +10,7 @@ use super::Binder;
 use crate::expression::ScalarExpression;
 use crate::storage::Storage;
 use crate::types::LogicalType;
+use crate::types::value::DataValue;
 
 impl<S: Storage> Binder<S> {
     #[async_recursion]
@@ -135,6 +136,7 @@ impl<S: Storage> Binder<S> {
             };
             match arg_expr {
                 FunctionArgExpr::Expr(expr) => args.push(self.bind_expr(expr).await?),
+                FunctionArgExpr::Wildcard => args.push(Self::wildcard_expr()),
                 _ => todo!()
             }
         }
@@ -174,4 +176,8 @@ impl<S: Storage> Binder<S> {
             _ => todo!(),
         })
     }
+
+    fn wildcard_expr() -> ScalarExpression {
+        ScalarExpression::Constant(Arc::new(DataValue::Utf8(Some("*".to_string()))))
+    }
 }

src/db.rs

@@ -227,6 +227,10 @@ mod test {
         let tuples_count_agg = kipsql.run("select count(d) from t2").await?;
         println!("{}", create_table(&tuples_count_agg));
 
+        println!("count wildcard agg:");
+        let tuples_count_wildcard_agg = kipsql.run("select count(*) from t2").await?;
+        println!("{}", create_table(&tuples_count_wildcard_agg));
+
         println!("count distinct agg:");
         let tuples_count_distinct_agg = kipsql.run("select count(distinct d) from t2").await?;
         println!("{}", create_table(&tuples_count_distinct_agg));