improved sql parser for mysql explain. for issue #1645

src/test/java/com/alibaba/druid/bvt/bug/Issue1645.java

@@ -0,0 +1,18 @@
+package com.alibaba.druid.bvt.bug;
+
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.util.JdbcConstants;
+import junit.framework.TestCase;
+
+/**
+ * Created by wenshao on 22/03/2017.
+ */
+public class Issue1645 extends TestCase {
+    public void test_for_issue() throws Exception {
+        String sql = "explain extended select * from foo";
+        String formatedSql = SQLUtils.format(sql, JdbcConstants.MYSQL);
+        assertEquals("EXPLAIN extended\n" +
+                "SELECT *\n" +
+                "FROM foo", formatedSql);
+    }
+}