odps sql parser support drop table purge. issue #1496

src/main/java/com/alibaba/druid/sql/parser/SQLStatementParser.java

@@ -1182,7 +1182,7 @@ public class SQLStatementParser extends SQLParser {
                 continue;
             }
 
-            if (lexer.token() == Token.PURGE) {
+            if (lexer.token() == Token.PURGE || identifierEquals("PURGE")) {
                 lexer.nextToken();
                 stmt.setPurge(true);
                 continue;

src/test/java/com/alibaba/druid/bvt/sql/odps/OdpsDropTableTest.java

@@ -0,0 +1,14 @@
+package com.alibaba.druid.bvt.sql.odps;
+
+import com.alibaba.druid.sql.SQLUtils;
+import junit.framework.TestCase;
+
+/**
+ * Created by wenshao on 2016/11/18.
+ */
+public class OdpsDropTableTest extends TestCase {
+    public void test_drop_table() throws Exception {
+        String sql = "DROP TABLE a PURGE ;";
+        assertEquals("DROP TABLE a PURGE;", SQLUtils.formatOdps(sql));
+    }
+}