From b4f345fb7af06abdb0dff04ef26fc16f5c9d6140 Mon Sep 17 00:00:00 2001
From: wenshao <szujobs@hotmail.com>
Date: Mon, 26 Aug 2013 19:12:52 +0800
Subject: [PATCH] improve sql wall

---
 .../com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java | 7 +++++--
 src/main/java/com/alibaba/druid/wall/WallProvider.java     | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java b/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java
index 2124c7a324..37489d6a5f 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java
@@ -961,8 +961,11 @@ public class SQLEvalVisitorUtils {
                 x.putAttribute(EVAL_VALUE, value);
                 break;
             case IsNot:
-                value = !eq(leftValue, rightValue);
-                x.putAttribute(EVAL_VALUE, value);
+                if (leftValue == EVAL_VALUE_NULL) {
+                    x.putAttribute(EVAL_VALUE, false);
+                } else if (leftValue != null) {
+                    x.putAttribute(EVAL_VALUE, true);
+                }
                 break;
             case RegExp:
             case RLike: {
diff --git a/src/main/java/com/alibaba/druid/wall/WallProvider.java b/src/main/java/com/alibaba/druid/wall/WallProvider.java
index 394b507345..69aa1eb2bd 100644
--- a/src/main/java/com/alibaba/druid/wall/WallProvider.java
+++ b/src/main/java/com/alibaba/druid/wall/WallProvider.java
@@ -60,7 +60,7 @@ public abstract class WallProvider {
 
     private int                                           MAX_SQL_LENGTH          = 2048;                                              // 1k
 
-    private int                                           whiteSqlMaxSize         = 500;                                               // 1k
+    private int                                           whiteSqlMaxSize         = 1000;                                               // 1k
 
     private boolean                                       blackListEnable         = true;
     private LRUCache<String, WallSqlStat>                 blackList;