diff --git a/EdgeManager/EController/EConfigure.php b/EdgeManager/EController/EConfigure.php
index 02b367c..bc3296e 100644
--- a/EdgeManager/EController/EConfigure.php
+++ b/EdgeManager/EController/EConfigure.php
@@ -50,30 +50,13 @@ class EConfigure {
     }
 
     function remove_server() {
-        pg_query($this -> dbconn, "BEGIN");
-        $exists = pg_query($this -> dbconn, sprintf(
-            "SELECT EXISTS(
-                SELECT 1 FROM hf_mes_scada_edgeserver_controller_device
-                WHERE server_id = '%s'
-            )", $this -> post -> id
-        ));
-        if (pg_fetch_assoc($exists)['exists'] === 't') {
-            pg_query($this -> dbconn, "ROLLBACK");
-            return "REMAINING";
-        } else {
-            $res = pg_delete(
-                $this -> dbconn,
-                'hf_mes_scada_edgeserver_controller_server',
-                (array) $this -> post,
-            );
-            if ($res) {
-                pg_query($this -> dbconn, "COMMIT");
-                return true;
-            } else {
-                pg_query($this -> dbconn, "ROLLBACK");
-                return false;
-            }
-        }
+        $res = pg_delete(
+            $this -> dbconn,
+            'hf_mes_scada_edgeserver_controller_server',
+            (array) $this -> post,
+        );
+
+        return $res ? true : "REMAINING";
     }
     
     function update_server() {
diff --git a/EdgeManager/Init.php b/EdgeManager/Init.php
index f77e4c3..1a0f80a 100644
--- a/EdgeManager/Init.php
+++ b/EdgeManager/Init.php
@@ -12,8 +12,20 @@ function init_db($server_name, $port, $user, $password) {
     pg_query($dbconn, "CREATE EXTENSION IF NOT EXISTS timescaledb");
     pg_query(
         $dbconn,
-        "CREATE TYPE category
-        AS ENUM ('DEVICE_STATUS', 'ITEM_ID', 'DEVICE_DATA', 'PROCESS_DATA', 'RESULT_DATA', 'STATISTICAL_DATA')"
+        "DO $$ BEGIN
+            CREATE TYPE category
+            AS ENUM (
+                'DEVICE_STATUS',
+                'ITEM_ID',
+                'DEVICE_DATA',
+                'PROCESS_DATA',
+                'RESULT_DATA',
+                'STATISTICAL_DATA'
+            );
+        EXCEPTION
+            WHEN duplicate_object
+            THEN null;
+        END $$"
     );
     pg_query($dbconn, "CREATE TABLE IF NOT EXISTS hf_mes_scada_data_capture_node_configure (
         id serial2 primary key,
@@ -42,14 +54,17 @@ function init_db($server_name, $port, $user, $password) {
         id serial2 primary key,
         code text,
         name text NOT NULL,
-        server_id serial2 references hf_mes_scada_edgeserver_controller_server(id),
+        server_id serial2
+            REFERENCES hf_mes_scada_edgeserver_controller_server(id),
         conf json,
         create_date timestamp NOT NULL DEFAULT NOW(),
         note text
     )");
     pg_query($dbconn, "CREATE TABLE IF NOT EXISTS hf_mes_scada_edgeserver_controller_command (
         id serial8 primary key,
-        server_id serial2 references hf_mes_scada_edgeserver_controller_server(id),
+        server_id serial2
+            REFERENCES hf_mes_scada_edgeserver_controller_server(id)
+            ON DELETE CASCADE,
         device_name text,
         command text,
         create_date timestamp NOT NULL DEFAULT NOW(),