diff --git a/classes/db/DB.class.php b/classes/db/DB.class.php
index 9e973a3b6..b18a99f66 100644
--- a/classes/db/DB.class.php
+++ b/classes/db/DB.class.php
@@ -373,37 +373,37 @@
         function getConditionPart($name, $value, $operation) {
             switch($operation) {
                 case 'equal' :
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' = '.$value;
                     break;
                 case 'more' :
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' >= '.$value;
                     break;
                 case 'excess' :
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' > '.$value;
                     break;
                 case 'less' :
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' <= '.$value;
                     break;
                 case 'below' : 
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' < '.$value;
                     break;
                 case 'like_tail' : 
                 case 'like_prefix' : 
                 case 'like' : 
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' like '.$value;
                     break;
                 case 'in' : 
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' in ('.$value.')';
                     break;
                 case 'notequal' : 
-                        if(!$value) return;
+                        if(!isset($value)) return;
                         return $name.' <> '.$value;
                     break;
                 case 'notnull' : 
diff --git a/classes/db/DBCubrid.class.php b/classes/db/DBCubrid.class.php
index e8ddca98d..326973672 100644
--- a/classes/db/DBCubrid.class.php
+++ b/classes/db/DBCubrid.class.php
@@ -381,7 +381,7 @@
             foreach($output->conditions as $key => $val) {
                 $sub_condition = '';
                 foreach($val['condition'] as $k =>$v) {
-                    if(!$v['value']) continue;
+                    if(!isset($v['value'])) continue;
 
                     $name = $v['column'];
                     $operation = $v['operation'];
diff --git a/classes/db/DBFirebird.class.php b/classes/db/DBFirebird.class.php
index aa00106b9..c73c35525 100644
--- a/classes/db/DBFirebird.class.php
+++ b/classes/db/DBFirebird.class.php
@@ -592,7 +592,7 @@
             foreach($output->conditions as $key => $val) {
                 $sub_condition = '';
                 foreach($val['condition'] as $k =>$v) {
-                    if(!$v['value']) continue;
+                    if(!isset($v['value'])) continue;
 
                     $name = $v['column'];
                     $operation = $v['operation'];
diff --git a/classes/db/DBMysql.class.php b/classes/db/DBMysql.class.php
index a0875db52..5941d371e 100644
--- a/classes/db/DBMysql.class.php
+++ b/classes/db/DBMysql.class.php
@@ -369,7 +369,7 @@
             foreach($output->conditions as $key => $val) {
                 $sub_condition = '';
                 foreach($val['condition'] as $k =>$v) {
-                    if(!$v['value']) continue;
+                    if(!isset($v['value'])) continue;
 
                     $name = $v['column'];
                     $operation = $v['operation'];
diff --git a/classes/db/DBMysql_innodb.class.php b/classes/db/DBMysql_innodb.class.php
index aebf7a07d..08f99a047 100644
--- a/classes/db/DBMysql_innodb.class.php
+++ b/classes/db/DBMysql_innodb.class.php
@@ -379,7 +379,7 @@
             foreach($output->conditions as $key => $val) {
                 $sub_condition = '';
                 foreach($val['condition'] as $k =>$v) {
-                    if(!$v['value']) continue;
+                    if(!isset($v['value'])) continue;
 
                     $name = $v['column'];
                     $operation = $v['operation'];
diff --git a/classes/db/DBPostgresql.class.php b/classes/db/DBPostgresql.class.php
index 545527fb4..c964b5791 100644
--- a/classes/db/DBPostgresql.class.php
+++ b/classes/db/DBPostgresql.class.php
@@ -371,7 +371,7 @@
             foreach($output->conditions as $key => $val) {
                 $sub_condition = '';
                 foreach($val['condition'] as $k =>$v) {
-                    if(!$v['value']) continue;
+                    if(!isset($v['value'])) continue;
 
                     $name = $v['column'];
                     $operation = $v['operation'];
diff --git a/classes/db/DBSqlite2.class.php b/classes/db/DBSqlite2.class.php
index 6a993b2eb..df7f517b7 100644
--- a/classes/db/DBSqlite2.class.php
+++ b/classes/db/DBSqlite2.class.php
@@ -352,7 +352,7 @@
             foreach($output->conditions as $key => $val) {
                 $sub_condition = '';
                 foreach($val['condition'] as $k =>$v) {
-                    if(!$v['value']) continue;
+                    if(!isset($v['value'])) continue;
 
                     $name = $v['column'];
                     $operation = $v['operation'];
diff --git a/classes/db/DBSqlite3_pdo.class.php b/classes/db/DBSqlite3_pdo.class.php
index 03de0920f..f8cd32b44 100644
--- a/classes/db/DBSqlite3_pdo.class.php
+++ b/classes/db/DBSqlite3_pdo.class.php
@@ -381,7 +381,7 @@
             foreach($output->conditions as $key => $val) {
                 $sub_condition = '';
                 foreach($val['condition'] as $k =>$v) {
-                    if(!$v['value']) continue;
+                    if(!isset($v['value'])) continue;
 
                     $name = $v['column'];
                     $operation = $v['operation'];