diff --git a/src/core/operation/Delete.java b/src/core/operation/Delete.java
new file mode 100644
index 0000000..c9a78c5
--- /dev/null
+++ b/src/core/operation/Delete.java
@@ -0,0 +1,15 @@
+package core.operation;
+
+import core.user.User;
+import dao.DBManagement;
+import error.GExcptSQL;
+
+public class Delete extends Operation {
+    @Override
+    public void execute(User subject) throws GExcptSQL {
+        String id = (String)options.get("id");
+        String sql = "DELETE FROM graduation_design WHERE id = \'"+
+                id+"\'";
+        DBManagement.update(sql);
+    }
+}
diff --git a/src/core/operation/Delete.json b/src/core/operation/Delete.json
new file mode 100644
index 0000000..183384f
--- /dev/null
+++ b/src/core/operation/Delete.json
@@ -0,0 +1,3 @@
+{
+  "id": "java.lang.String"
+}
\ No newline at end of file
diff --git a/src/core/operation/DownloadFile.java b/src/core/operation/DownloadFile.java
new file mode 100644
index 0000000..1154c74
--- /dev/null
+++ b/src/core/operation/DownloadFile.java
@@ -0,0 +1,4 @@
+package core.operation;
+
+public class DownloadFile {
+}
diff --git a/src/core/operation/FillInformation.java b/src/core/operation/FillInformation.java
new file mode 100644
index 0000000..4c954b2
--- /dev/null
+++ b/src/core/operation/FillInformation.java
@@ -0,0 +1,4 @@
+package core.operation;
+
+public class FillInformation {
+}
diff --git a/src/core/operation/Operation.java b/src/core/operation/Operation.java
index 195dbfa..7c7971f 100644
--- a/src/core/operation/Operation.java
+++ b/src/core/operation/Operation.java
@@ -9,8 +9,8 @@ import java.util.Map;
 
 public abstract class Operation {
 
-    private Map<String, Object> options;
-    private User subject;
+    protected Map<String, Object> options;
+    protected User subject;
     Operation(){
         super();
     }
@@ -38,6 +38,6 @@ public abstract class Operation {
         }
         this.options.put(key,value);
     }
-    public abstract void execute(User subject) throws GExcptSQL;
+    public abstract void execute(User subject) throws Exception;
 
 }
diff --git a/src/core/operation/Search.java b/src/core/operation/Search.java
new file mode 100644
index 0000000..5176b57
--- /dev/null
+++ b/src/core/operation/Search.java
@@ -0,0 +1,22 @@
+package core.operation;
+
+import core.user.User;
+import dao.DBManagement;
+
+import java.sql.ResultSet;
+
+public class Search extends Operation {
+    @Override
+    public void execute(User subject) throws Exception {
+        String table = (String)options.get("table");
+        String field = (String)options.get("field");
+        String value = (String)options.get("value");
+        int start = (int)options.get("start");
+        int end = (int)options.get("end");
+        String sql = "SELECT * FROM "+table+
+                " WHERE "+field+" = \'"+value+"\'"+
+                " limit "+start+", "+end;
+        ResultSet rs = DBManagement.query(sql);
+        //todo
+    }
+}
diff --git a/src/core/operation/Search.json b/src/core/operation/Search.json
new file mode 100644
index 0000000..38d8115
--- /dev/null
+++ b/src/core/operation/Search.json
@@ -0,0 +1,8 @@
+{
+  "table": "java.lang.String",
+  "field": "java.lang.String",
+  "value": "java.lang.String",
+  "start": "int",
+  "end": "int",
+  "return": "java.lang.String[][]"
+}
\ No newline at end of file
diff --git a/src/core/operation/Select.java b/src/core/operation/Select.java
index 3ea81dd..f58ea03 100644
--- a/src/core/operation/Select.java
+++ b/src/core/operation/Select.java
@@ -8,11 +8,15 @@ import java.util.Map;
 
 public class Select extends Operation {
 
-    private Map<String, Object> options;
-    private User subject;
     @Override
     public void execute(User subject) throws GExcptSQL {
-        this.setSubject(subject);
-        DBManagement.update("update stu ");
+        String student_id = (String)options.get("student_id");
+        String teacher_id = (String)options.get("teacher_id");
+        String id = student_id;
+        String sql = "INSERT INTO graduation_design VALUES (\'"+
+                id+"\', "+
+                student_id+"\', "+
+                teacher_id+"\', \'m\', \'m\')";
+        DBManagement.update(sql);
     }
 }
diff --git a/src/core/operation/Select.json b/src/core/operation/Select.json
new file mode 100644
index 0000000..6b2332b
--- /dev/null
+++ b/src/core/operation/Select.json
@@ -0,0 +1,4 @@
+{
+  "student_id": "java.lang.String",
+  "teacher_id": "java.lang.String"
+}
\ No newline at end of file