diff --git a/modules/install/install.controller.php b/modules/install/install.controller.php
index da20fcf5a..94f48ae70 100644
--- a/modules/install/install.controller.php
+++ b/modules/install/install.controller.php
@@ -437,7 +437,7 @@
                 $buff .= 'array(';
                 foreach($con_string as $k => $v){
                     if(in_array($k, array('resource', 'is_connected'))) continue;
-                    if($k == 'db_table_prefix'){
+                    if($k == 'db_table_prefix' && !empty($v)){
                            if(substr($v,-1)!='_') $v .= '_';
                     }
                     $buff .= "'$k' => '$v',";
diff --git a/modules/install/ruleset/cubrid.xml b/modules/install/ruleset/cubrid.xml
index e8efb3671..7d06396b7 100644
--- a/modules/install/ruleset/cubrid.xml
+++ b/modules/install/ruleset/cubrid.xml
@@ -9,6 +9,6 @@
 		<field name="db_userid" required="true" length="1:250" rule="alpha_number" />
 		<field name="db_password" required="true" length="1:250"/>
 		<field name="db_database" required="true" length="1:250" />
-		<field name="db_table_prefix" required="true" length="2:20" rule="alpha" default="xe" />
+		<field name="db_table_prefix" length="2:20" rule="alpha" />
     </fields>
 </ruleset>
diff --git a/modules/install/ruleset/firebird.xml b/modules/install/ruleset/firebird.xml
index e8efb3671..7d06396b7 100644
--- a/modules/install/ruleset/firebird.xml
+++ b/modules/install/ruleset/firebird.xml
@@ -9,6 +9,6 @@
 		<field name="db_userid" required="true" length="1:250" rule="alpha_number" />
 		<field name="db_password" required="true" length="1:250"/>
 		<field name="db_database" required="true" length="1:250" />
-		<field name="db_table_prefix" required="true" length="2:20" rule="alpha" default="xe" />
+		<field name="db_table_prefix" length="2:20" rule="alpha" />
     </fields>
 </ruleset>
diff --git a/modules/install/ruleset/mssql.xml b/modules/install/ruleset/mssql.xml
index e8efb3671..7d06396b7 100644
--- a/modules/install/ruleset/mssql.xml
+++ b/modules/install/ruleset/mssql.xml
@@ -9,6 +9,6 @@
 		<field name="db_userid" required="true" length="1:250" rule="alpha_number" />
 		<field name="db_password" required="true" length="1:250"/>
 		<field name="db_database" required="true" length="1:250" />
-		<field name="db_table_prefix" required="true" length="2:20" rule="alpha" default="xe" />
+		<field name="db_table_prefix" length="2:20" rule="alpha" />
     </fields>
 </ruleset>
diff --git a/modules/install/ruleset/mysql.xml b/modules/install/ruleset/mysql.xml
index e8efb3671..7d06396b7 100644
--- a/modules/install/ruleset/mysql.xml
+++ b/modules/install/ruleset/mysql.xml
@@ -9,6 +9,6 @@
 		<field name="db_userid" required="true" length="1:250" rule="alpha_number" />
 		<field name="db_password" required="true" length="1:250"/>
 		<field name="db_database" required="true" length="1:250" />
-		<field name="db_table_prefix" required="true" length="2:20" rule="alpha" default="xe" />
+		<field name="db_table_prefix" length="2:20" rule="alpha" />
     </fields>
 </ruleset>
diff --git a/modules/install/ruleset/postgresql.xml b/modules/install/ruleset/postgresql.xml
index e8efb3671..7d06396b7 100644
--- a/modules/install/ruleset/postgresql.xml
+++ b/modules/install/ruleset/postgresql.xml
@@ -9,6 +9,6 @@
 		<field name="db_userid" required="true" length="1:250" rule="alpha_number" />
 		<field name="db_password" required="true" length="1:250"/>
 		<field name="db_database" required="true" length="1:250" />
-		<field name="db_table_prefix" required="true" length="2:20" rule="alpha" default="xe" />
+		<field name="db_table_prefix" length="2:20" rule="alpha" />
     </fields>
 </ruleset>
diff --git a/modules/install/ruleset/sqlite.xml b/modules/install/ruleset/sqlite.xml
index d3ed86ceb..7aa3a18fc 100644
--- a/modules/install/ruleset/sqlite.xml
+++ b/modules/install/ruleset/sqlite.xml
@@ -5,6 +5,6 @@
     <fields>
 		<field name="db_type" required="true" default="mysql" />
 		<field name="db_database" required="true" length="1:250" />
-		<field name="db_table_prefix" required="true" length="2:20" rule="alpha" default="xe" />
+		<field name="db_table_prefix" length="2:20" rule="alpha" />
     </fields>
 </ruleset>