From f8d29879310705ca0c9dd8da02c83c09a8792420 Mon Sep 17 00:00:00 2001
From: yakolee <yakolyh@gmail.com>
Date: Fri, 6 Jun 2014 18:43:49 +0800
Subject: [PATCH] bugfix

---
 .../sql/visitor/SQLEvalVisitorUtils.java      | 25 ++++++++++++++++++-
 .../sql/visitor/functions/Substring.java      |  4 +--
 2 files changed, 26 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 a6f626cce2..7564d5f2c2 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/SQLEvalVisitorUtils.java
@@ -1418,6 +1418,18 @@ public class SQLEvalVisitorUtils {
         if (a == null || b == null) {
             return null;
         }
+        
+        if(a == EVAL_VALUE_NULL || b == EVAL_VALUE_NULL) {
+            return null;
+        }
+        
+        if (a instanceof String) {
+            a = castToNumber((String) a);
+        }
+
+        if (b instanceof String) {
+            b = castToNumber((String) b);
+        }
 
         if (a instanceof Long || b instanceof Long) {
             return castToLong(a).longValue() & castToLong(b).longValue();
@@ -1503,7 +1515,18 @@ public class SQLEvalVisitorUtils {
         }
 
         if (a instanceof Long || b instanceof Long) {
-            return castToLong(a) / castToLong(b);
+            Long longA = castToLong(a);
+            Long longB = castToLong(b);
+            if (longB == 0) {
+                if (longA > 0) {
+                    return Double.POSITIVE_INFINITY;
+                } else if (longA < 0) {
+                    return Double.NEGATIVE_INFINITY;
+                } else {
+                    return Double.NaN;
+                }
+            }
+            return longA / longB;
         }
 
         if (a instanceof Integer || b instanceof Integer) {
diff --git a/src/main/java/com/alibaba/druid/sql/visitor/functions/Substring.java b/src/main/java/com/alibaba/druid/sql/visitor/functions/Substring.java
index 9e11949825..fe6ecb9914 100644
--- a/src/main/java/com/alibaba/druid/sql/visitor/functions/Substring.java
+++ b/src/main/java/com/alibaba/druid/sql/visitor/functions/Substring.java
@@ -50,7 +50,7 @@ public class Substring implements Function {
 
         if (paramSize == 2) {
 
-            if (index < 0) {
+            if (index <= 0) {
                 int lastIndex = str.length() + index;
                 return str.substring(lastIndex);
             }
@@ -68,7 +68,7 @@ public class Substring implements Function {
         int len = ((Number) param2Value).intValue();
 
         String result;
-        if (index < 0) {
+        if (index <= 0) {
             int lastIndex = str.length() + index;
             result = str.substring(lastIndex);
         } else {