JaQu improvements

h2/src/test/org/h2/test/jaqu/SamplesTest.java

@@ -49,13 +49,14 @@ public class SamplesTest extends TestBase {
         db.insertAll(Product.getProductList());
         db.insertAll(Customer.getCustomerList());
         db.insertAll(Order.getOrderList());
-        // TODO SUM, MIN, MAX, LIKE, LIKE ESCAPE...
+        // TODO MIN, MAX, LIKE, LIKE ESCAPE...
         // TODO +, -, *, /, ||, nested operations
         // TODO nested AND/OR
         // TODO NOT
         // TODO DELETE: FROM ... DELETE?
         // TODO UPDATE: FROM ... UPDATE?
         // TODO SELECT UNION
+        testSum();
         testLength();
         testCount();
         testGroup();
@@ -254,6 +255,16 @@ public class SamplesTest extends TestBase {
         assertEquals("[4, 5]", s);
     }
     
+    private void testSum() throws Exception {
+        Product p = new Product();
+        Integer sum = db.from(p).
+            selectFirst(sum(p.unitsInStock));
+        assertEquals(323, sum.intValue());
+        Double sumPrice = db.from(p).
+        selectFirst(sum(p.unitPrice));
+        assertEquals(313.35, sumPrice.doubleValue());
+    }
+    
     private void testCount() throws Exception {
         long count = db.from(new Product()).selectCount();
         assertEquals(10, count);

h2/src/tools/org/h2/jaqu/Function.java

@@ -39,6 +39,11 @@ public class Function implements Token {
             Utils.newObject(Integer.class), new Function("LENGTH", x));
     }
 
+    public static <T extends Number> T sum(T x) {
+        return (T) Db.registerToken(
+            Utils.newObject(x.getClass()), new Function("SUM", x));
+    }
+
     public static Long count(Object x) {
         return Db.registerToken(
             Utils.newObject(Long.class), new Function("COUNT", x));

h2/src/tools/org/h2/jaqu/Query.java

@@ -63,6 +63,11 @@ public class Query<T> {
         return select(true);
     }
     
+    public <X, Z> X selectFirst(Z x) {
+        List<X> list = (List<X>) select(x);
+        return list.isEmpty() ? null : list.get(0);
+    }
+
     private List<T> select(boolean distinct) {
         List<T> result = Utils.newArrayList();
         ResultSet rs = db.executeQuery(getSQL("*", distinct));

h2/src/tools/org/h2/jaqu/QueryWhere.java

@@ -42,6 +42,11 @@ public class QueryWhere<T> {
         return (List<X>) query.selectDistinct(x);
     }
 
+    public <X, Z> X selectFirst(Z x) {
+        List<X> list = (List<X>) query.select(x);
+        return list.isEmpty() ? null : list.get(0);
+    }
+
     public List<T> select() {
         return query.select();
     }