fixes #165

Author: wumpz

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -1961,7 +1961,8 @@ IntervalExpression IntervalExpression() : {
 	Token token;
 }
 {
-	<K_INTERVAL> token=<S_CHAR_LITERAL> { interval.setParameter(token.image); }
+	<K_INTERVAL> (token=<S_LONG> | token=<S_DOUBLE> | token=<S_CHAR_LITERAL>) 
+    { interval.setParameter(token.image); }
     [ LOOKAHEAD(2) token = <S_IDENTIFIER> { interval.setIntervalType(token.image); } ]
 	{
 		return interval;

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

@@ -1600,7 +1600,12 @@ public void testInterval3() throws JSQLParserException {
         String stmt = "SELECT 5 + INTERVAL '3' day";
         assertSqlCanBeParsedAndDeparsed(stmt);
     }
-
+    
+    public void testInterval4() throws JSQLParserException {
+        String stmt = "SELECT '2008-12-31 23:59:59' + INTERVAL 1 SECOND";
+        assertSqlCanBeParsedAndDeparsed(stmt);
+    }
+    
     public void testMultiValueIn() throws JSQLParserException {
         String stmt = "SELECT * FROM mytable WHERE (a, b, c) IN (SELECT a, b, c FROM mytable2)";
         assertSqlCanBeParsedAndDeparsed(stmt);