Merge origin/master

Author: wumpz

src/test/java/net/sf/jsqlparser/test/select/SelectTest.java

@@ -2196,7 +2196,7 @@ public void testTopExpressionIssue243_2() throws JSQLParserException {
         assertSqlCanBeParsedAndDeparsed("SELECT TOP (CAST(? AS INT)) * FROM MyTable");
     }
 
-    public void testKeywordTop() throws JSQLParserException {
-        assertSqlCanBeParsedAndDeparsed("SELECT @top");
+    public void testFunctionIssue284() throws JSQLParserException {
+        assertSqlCanBeParsedAndDeparsed("SELECT NVL((SELECT 1 FROM DUAL), 1) AS A FROM TEST1");
     }
 }