Update QueryBuilder.

README.md

@@ -872,7 +872,7 @@ Primary and foreign key annotations associated with the [`Actor`](kilo-test/src/
 select actor.* from actor 
 join film_actor on actor.actor_id = film_actor.actor_id 
 where film_actor.film_id = :filmID
-order by actor.last_name asc, actor.first_name asc
+order by last_name asc, first_name asc
 ```
 
 Insert, update, and delete operations are also supported. See the [pet](kilo-test/src/main/java/org/httprpc/kilo/test/PetService.java), [catalog](kilo-test/src/main/java/org/httprpc/kilo/test/CatalogService.java), and [film](kilo-test/src/main/java/org/httprpc/kilo/test/FilmService.java) service examples for more information.

kilo-client/src/main/java/org/httprpc/kilo/sql/QueryBuilder.java

@@ -522,6 +522,28 @@ private static String getForeignKeyColumnName(Class<?> from, Class<?> to) {
         throw new UnsupportedOperationException("Foreign key is not defined.");
     }
 
+    /**
+     * Appends a "union" operation.
+     *
+     * @param queryBuilder
+     * A "select" query.
+     *
+     * @return
+     * The {@link QueryBuilder} instance.
+     */
+    public QueryBuilder union(QueryBuilder queryBuilder) {
+        if (queryBuilder == null) {
+            throw new IllegalArgumentException();
+        }
+
+        sqlBuilder.append(" union ");
+        sqlBuilder.append(queryBuilder);
+
+        parameters.addAll(queryBuilder.parameters);
+
+        return this;
+    }
+
     /**
      * Creates an "insert" query.
      *
@@ -1040,6 +1062,10 @@ private QueryBuilder filterByIndex(String operator, String... keys) {
      * The {@link QueryBuilder} instance.
      */
     public QueryBuilder filterByExists(QueryBuilder queryBuilder) {
+        if (queryBuilder == null) {
+            throw new IllegalArgumentException();
+        }
+
         sqlBuilder.append(" ");
         sqlBuilder.append(filterCount == 0 ? WHERE : AND);
         sqlBuilder.append(" exists (");
@@ -1063,6 +1089,10 @@ public QueryBuilder filterByExists(QueryBuilder queryBuilder) {
      * The {@link QueryBuilder} instance.
      */
     public QueryBuilder filterByNotExists(QueryBuilder queryBuilder) {
+        if (queryBuilder == null) {
+            throw new IllegalArgumentException();
+        }
+
         sqlBuilder.append(" ");
         sqlBuilder.append(filterCount == 0 ? WHERE : AND);
         sqlBuilder.append(" not exists (");
@@ -1088,8 +1118,6 @@ public QueryBuilder filterByNotExists(QueryBuilder queryBuilder) {
     public QueryBuilder ordered(boolean ascending) {
         var first = types.getFirst();
 
-        var tableName = getTableName(first);
-
         sqlBuilder.append(" order by ");
 
         var i = 0;
@@ -1099,8 +1127,6 @@ public QueryBuilder ordered(boolean ascending) {
                 sqlBuilder.append(", ");
             }
 
-            sqlBuilder.append(tableName);
-            sqlBuilder.append(".");
             sqlBuilder.append(indexColumnName);
             sqlBuilder.append(" ");
             sqlBuilder.append(ascending ? "asc" : "desc");

kilo-client/src/test/java/org/httprpc/kilo/sql/QueryBuilderTest.java

@@ -315,7 +315,7 @@ public void testSelectIHGF() {
             + "join H on I.h = H.h "
             + "join G on H.g = G.g "
             + "where G.f = ? "
-            + "order by I.t asc, I.u asc", queryBuilder.toString());
+            + "order by t asc, u asc", queryBuilder.toString());
 
         assertEquals(listOf("f"), getParameters(queryBuilder));
     }
@@ -332,7 +332,7 @@ public void testSelectIJK() {
             + "join J on I.i = J.i "
             + "join K on J.i = K.i "
             + "where I.i = ? "
-            + "order by I.t desc, I.u desc", queryBuilder.toString());
+            + "order by t desc, u desc", queryBuilder.toString());
 
         assertEquals(listOf("i"), getParameters(queryBuilder));
     }
@@ -431,6 +431,14 @@ public void testNotExists() {
         assertEquals(listOf("b"), getParameters(queryBuilder));
     }
 
+    @Test
+    public void testUnion() {
+        var queryBuilder = QueryBuilder.select(A.class).filterByPrimaryKey("a1").union(QueryBuilder.select(A.class).filterByPrimaryKey("a2"));
+
+        assertEquals("select A.a, A.b, A.c, A.d as x from A where A.a = ? union select A.a, A.b, A.c, A.d as x from A where A.a = ?", queryBuilder.toString());
+        assertEquals(listOf("a1", "a2"), getParameters(queryBuilder));
+    }
+
     @Test
     public void testInsert() {
         var queryBuilder = QueryBuilder.insert(A.class);