diff --git a/htdocs/lib/Database/DBStudyActivity.php b/htdocs/lib/Database/DBStudyActivity.php
index ec607a1..2940e8a 100644
--- a/htdocs/lib/Database/DBStudyActivity.php
+++ b/htdocs/lib/Database/DBStudyActivity.php
@@ -157,7 +157,7 @@ class DBStudyActivity extends Database {
     protected function queryActivityByWhere($where) {
 
         $sqlString = "SELECT `SaID`, `UID`, `ThID`, ".
-                     "(SELECT `ThName` FROM `chu__Theme` AS `th` ".
+                     "(SELECT `ThName` FROM `".$this->table('Theme')."` AS `th` ".
                      "WHERE `th`.`ThID` = `sa`.`ThID`) AS `ThName`, ".
                      "`StartTime`, ".
                      "FROM_UNIXTIME(UNIX_TIMESTAMP(`StartTime`)+(`LearnTime`+`Delay`)*60)".
diff --git a/htdocs/lib/Database/DBTheme.php b/htdocs/lib/Database/DBTheme.php
index 256f460..7a4a977 100644
--- a/htdocs/lib/Database/DBTheme.php
+++ b/htdocs/lib/Database/DBTheme.php
@@ -30,7 +30,7 @@ class DBTheme extends Database {
         $sqlString = "SELECT `ThID`, `ThName`, ".
                      "`ThLearnTime`, `StartTID`, `ThIntroduction`, ".
                      "`ThBuildTime`, `ThModifyTime`, ".
-                     "(SELECT count(`TID`) FROM `chu__TBelong` AS `belong`
+                     "(SELECT count(`TID`) FROM `".$this->table('TBelong')."` AS `belong`
                      WHERE `belong`.`ThID` = `theme`.`ThID`) AS `TargetTotal`".
                      "FROM `".$this->table('Theme')."` AS `theme` ".
                      "WHERE ".$where;