diff --git a/src/com/szpg/db/dao/impl/PgPowerDaoImpl.java b/src/com/szpg/db/dao/impl/PgPowerDaoImpl.java
index 7941cb1..a630a7b 100644
--- a/src/com/szpg/db/dao/impl/PgPowerDaoImpl.java
+++ b/src/com/szpg/db/dao/impl/PgPowerDaoImpl.java
@@ -127,8 +127,10 @@
 	@Override
 	public PgPower findLatestPowerByDevice(Integer deviceid) {
 		Connection conn = null;
-		
-		String queryStr = "SELECT ID, AU, BU, CU, AI, BI, CI, LOGTIME, PGDEVICEID FROM PG_POWER WHERE PGDEVICEID = ? AND ROWNUM <= 5 ORDER BY LOGTIME DESC";
+
+		String queryStr = "SELECT A.* FROM " +
+				"(SELECT ID, AU, BU, CU, AI, BI, CI, LOGTIME, PGDEVICEID FROM PG_POWER WHERE PGDEVICEID = ? ORDER BY LOGTIME DESC) A " +
+				"WHERE ROWNUM <= 1";
 		Object[] param = new Object[1];
 		param[0] = deviceid;
 		try {