From 9744abaada6b106e13976738e8f721a7366872d2 Mon Sep 17 00:00:00 2001
From: wenshao <szujobs@hotmail.com>
Date: Mon, 3 Jun 2013 14:10:43 +0800
Subject: [PATCH] bug fixed for concat

---
 .../sql/visitor/SQLEvalVisitorUtils.java      |  4 ++
 .../druid/sql/visitor/functions/Concat.java   |  2 +-
 .../bvt/filter/wall/MySqlWallTest_concat.java | 39 +++++++++++++++++++
 3 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 src/test/java/com/alibaba/druid/bvt/filter/wall/MySqlWallTest_concat.java

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 c17eeaffe6..ea3922c745 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java
@@ -791,6 +791,10 @@ public class SQLEvalVisitorUtils {
         if (wallConditionContext != null) {
             wallConditionContext.setConstArithmetic(true);
         }
+        
+        if (leftValue == null || rightValue == null) {
+            return false;
+        }
 
         Object value = null;
         switch (x.getOperator()) {
diff --git a/src/main/java/com/alibaba/druid/sql/visitor/functions/Concat.java b/src/main/java/com/alibaba/druid/sql/visitor/functions/Concat.java
index 57aa04f7e7..43a805b216 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/functions/Concat.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/functions/Concat.java
@@ -33,7 +33,7 @@ public class Concat implements Function {
 
             Object itemValue = item.getAttributes().get(EVAL_VALUE);
             if (itemValue == null) {
-                continue;
+                return null;
             }
             buf.append(itemValue.toString());
         }
diff --git a/src/test/java/com/alibaba/druid/bvt/filter/wall/MySqlWallTest_concat.java b/src/test/java/com/alibaba/druid/bvt/filter/wall/MySqlWallTest_concat.java
new file mode 100644
index 0000000000..350186435e
--- /dev/null
+++ b/src/test/java/com/alibaba/druid/bvt/filter/wall/MySqlWallTest_concat.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.bvt.filter.wall;
+
+import junit.framework.TestCase;
+
+import org.junit.Assert;
+
+import com.alibaba.druid.wall.WallProvider;
+import com.alibaba.druid.wall.spi.MySqlWallProvider;
+
+public class MySqlWallTest_concat extends TestCase {
+
+    public void test_true() throws Exception {
+        WallProvider provider = new MySqlWallProvider();
+
+        provider.getConfig().setSelectHavingAlwayTrueCheck(true);
+
+        Assert.assertTrue(provider.checkValid(//
+        "select * from tb_product_word where name='' or CONCAT(name,style)='' or CONCAT(shop,style)=''  or CONCAT(ename,style)=''"));
+
+        Assert.assertEquals(1, provider.getTableStats().size());
+        Assert.assertTrue(provider.getTableStats().containsKey("tb_product_word"));
+    }
+
+}