diff --git a/src/core/operation/Delete.java b/src/core/operation/Delete.java
index c9a78c5..9982766 100644
--- a/src/core/operation/Delete.java
+++ b/src/core/operation/Delete.java
@@ -4,12 +4,16 @@ import core.user.User;
 import dao.DBManagement;
 import error.GExcptSQL;
 
+import java.util.HashMap;
+import java.util.Map;
+
 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);
+        Map<String, String> map = new HashMap<>();
+        map.put("id",(String)options.get("id"));
+        for(String table:DBManagement.graduationDesignTables){
+            DBManagement.delete(table,map);
+        }
     }
 }
diff --git a/src/core/operation/Search.java b/src/core/operation/Search.java
index 5176b57..73d0af1 100644
--- a/src/core/operation/Search.java
+++ b/src/core/operation/Search.java
@@ -4,19 +4,18 @@ import core.user.User;
 import dao.DBManagement;
 
 import java.sql.ResultSet;
+import java.util.List;
+import java.util.Map;
 
 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");
+        List<String> fields = (List<String>)options.get("fields");
+        Map<String, String> limits = (Map<String, String>)options.get("limits");
         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);
+        ResultSet rs = DBManagement.select(fields,table,limits,start,end);
         //todo
     }
 }
diff --git a/src/core/operation/Search.json b/src/core/operation/Search.json
index 38d8115..c8c3ac4 100644
--- a/src/core/operation/Search.json
+++ b/src/core/operation/Search.json
@@ -1,6 +1,6 @@
 {
   "table": "java.lang.String",
-  "field": "java.lang.String",
+  "fields": "java.util.List",
   "value": "java.lang.String",
   "start": "int",
   "end": "int",
diff --git a/src/core/operation/Select.java b/src/core/operation/Select.java
index f58ea03..c3f5f18 100644
--- a/src/core/operation/Select.java
+++ b/src/core/operation/Select.java
@@ -4,19 +4,24 @@ import core.user.User;
 import dao.DBManagement;
 import error.GExcptSQL;
 
+import java.util.HashMap;
 import java.util.Map;
 
 public class Select extends Operation {
 
     @Override
     public void execute(User subject) throws GExcptSQL {
-        String student_id = (String)options.get("student_id");
+        Map<String, String> vMap = new HashMap<>();
+        String 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);
+        vMap.put("id",id);
+        vMap.put("student_id",id);
+        vMap.put("teacher_id",teacher_id);
+        DBManagement.insert("graduation_design", vMap);
+        vMap.remove("student_id");
+        vMap.remove("teacher_id");
+        for(int i=1;i<DBManagement.graduationDesignTables.length;i++){
+            DBManagement.insert(DBManagement.graduationDesignTables[i],vMap);
+        }
     }
 }
diff --git a/src/core/process/AuxiliaryProcess.java b/src/core/process/AuxiliaryProcess.java
deleted file mode 100644
index 526c5fc..0000000
--- a/src/core/process/AuxiliaryProcess.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package core.process;
-
-public class AuxiliaryProcess extends Process {
-    public AuxiliaryProcess(String permission, String operationName, String processOptions, String info) throws Exception {
-        super(permission, operationName, processOptions, info);
-    }
-}
diff --git a/src/core/process/LastProcess.java b/src/core/process/LastProcess.java
deleted file mode 100644
index 4c48117..0000000
--- a/src/core/process/LastProcess.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package core.process;
-
-public class LastProcess extends Process{
-
-    public LastProcess(String permission, String operationName, String processOptions, String info) throws Exception {
-        super(permission, operationName, processOptions, info);
-    }
-}
diff --git a/src/core/process/Process.java b/src/core/process/Process.java
index bcdf14f..b4b818e 100644
--- a/src/core/process/Process.java
+++ b/src/core/process/Process.java
@@ -1,9 +1,6 @@
 package core.process;
 
 import core.operation.Operation;
-import core.user.User;
-import error.GExcptFactory;
-import error.GExcptSQL;
 
 public abstract class Process implements Cloneable{
 
@@ -11,48 +8,12 @@ public abstract class Process implements Cloneable{
     private Operation operation;
     private String buttonName;
     private String info;
-    private String processOptions;
-    private String UserOptions;
     @Override
     public Process clone(){
         //todo
         return null;
     }
-    public Process(String permission, String operationName, String processOptions, String info) throws Exception {
-        super();
-        this.setPermission(permission);
-        this.setOperation(operationName);
-        this.setInfo(info);
-        this.setProcessOptions(processOptions);
-        operation.setProcessOperations(processOptions);
-    }
 
-    public void setUserOperations(String key,Object value){
-        this.operation.addUserOperations(key,value);
-    }
-    public void execute(User subject) throws GExcptSQL {
-        this.operation.execute(subject);
-    }
-    private void setOperation(String operationName) throws GExcptFactory {
-        try {
-            this.operation = (Operation) core.utils.GetObjectByName.getOperationByName(operationName);
-        } catch (Exception e) {
-            throw new GExcptFactory("create"+operationName+"failure");
-        }
-    }
-
-    public void setInfo(String info) {
-        this.info = info;
-    }
-    public String getButtonName() {
-        return buttonName;
-    }
-    public void setButtonName(String buttonName) {
-        this.buttonName = buttonName;
-    }
-   public String getInfo() {
-        return info;
-    }
     public String getPermission() {
         return permission;
     }
@@ -69,12 +30,19 @@ public abstract class Process implements Cloneable{
         this.operation = operation;
     }
 
-    public String getProcessOptions() {
-        return processOptions;
+    public String getButtonName() {
+        return buttonName;
     }
 
-    public void setProcessOptions(String processOptions) {
-        this.processOptions = processOptions;
+    public void setButtonName(String buttonName) {
+        this.buttonName = buttonName;
     }
 
+    public String getInfo() {
+        return info;
+    }
+
+    public void setInfo(String info) {
+        this.info = info;
+    }
 }
diff --git a/src/core/process/ProcessManagement.java b/src/core/process/ProcessManagement.java
index aafefa0..88dcb8f 100644
--- a/src/core/process/ProcessManagement.java
+++ b/src/core/process/ProcessManagement.java
@@ -1,25 +1,9 @@
 package core.process;
-
-import java.io.File;
 import java.util.List;
-import java.util.Map;
 
 public class ProcessManagement {
-    private List<TemporaryProcess> temporaryProcesses;
-    private Map<String, List<Process>> lastProcesses;
-    private List<AuxiliaryProcess> auxiliaryProcesses;
-    public void setProcessesByJson(File file){
-        //todo
-    }
-    public Process getTemporaryProcess(int index){
-        return temporaryProcesses.get(index).clone();
-    }
     public Condition getCondition(String userType, List<Integer> index){
-        Condition condition = new Condition(this.lastProcesses.get(userType));
-        for(int i:index){
-            condition.add(getTemporaryProcess(i));
-        }
-        return condition;
+        return null;
     }
 
 }
diff --git a/src/core/process/TemporaryProcess.java b/src/core/process/TemporaryProcess.java
deleted file mode 100644
index 3f22949..0000000
--- a/src/core/process/TemporaryProcess.java
+++ /dev/null
@@ -1,9 +0,0 @@
-package core.process;
-
-
-
-public class TemporaryProcess extends Process {
-    public TemporaryProcess(String permission, String operationName, String processOptions, String info) throws Exception {
-        super(permission, operationName, processOptions, info);
-    }
-}
diff --git a/src/core/user/utils/AccountManagement.java b/src/core/user/utils/AccountManagement.java
index 7246b15..41db8ef 100644
--- a/src/core/user/utils/AccountManagement.java
+++ b/src/core/user/utils/AccountManagement.java
@@ -12,12 +12,9 @@ import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.List;
 
+import static dao.DBManagement.userTables;
+
 public interface AccountManagement {
-    static String[] userTables = {
-            "administrator",
-            "student",
-            "teacher"
-    };
     static User login(String id, String password) throws GExcptSQL, GExcptAccount, SQLException {
         ResultSet rs = null;
         String sql = null;
@@ -57,7 +54,7 @@ public interface AccountManagement {
         for(String info:necessaryInfo){
             sql+=info+"\', \'";
         }
-        sql =sql.substring(0,sql.length()-3)+")";
+        sql =Utils.cutTail(sql,3)+")";
         DBManagement.update(sql);
         return createUser(userType, necessaryInfo);
     }
diff --git a/src/dao/DBManagement.java b/src/dao/DBManagement.java
index c31829e..dd423cc 100644
--- a/src/dao/DBManagement.java
+++ b/src/dao/DBManagement.java
@@ -1,6 +1,8 @@
 package dao;
 
 import java.sql.*;
+import java.util.List;
+import java.util.Map;
 
 import error.GExcptSQL;
 import org.apache.tomcat.jdbc.pool.DataSource;
@@ -9,6 +11,24 @@ import org.apache.tomcat.jdbc.pool.PoolProperties;
 
 public class DBManagement {
 
+    public static String[] userTables = {
+            "administrator",
+            "student",
+            "teacher"
+    };
+    public static String[] graduationDesignTables = {
+        "graduation_design",
+        "graduation_design_finished_product",
+        "graduation_design_finished_product_mentor_score",
+        "graduation_design_finished_product_reviewer_score",
+        "graduation_design_information",
+        "graduation_design_opening_report",
+        "graduation_design_opening_report_opinion_record",
+        "graduation_design_reply",
+        "graduation_design_reply_opinion_record_score"
+    };
+
+
     static final String driverClassName="org.mariadb.jdbc.Driver";
     static final String url="jdbc:mariadb://localhost:3306/gdms";
     static final String username="gdms";
@@ -42,6 +62,26 @@ public class DBManagement {
         return null;
     }
 
+    public static void delete(String table, Map<String,String> limits) throws GExcptSQL {
+        Delete delete = new Delete(table, limits);
+        String sql = delete.getSQL();
+        update(sql);
+    }
+    public static void insert(String table, Map<String, String> vMap) throws GExcptSQL {
+        Insert insert = new Insert(table, vMap);
+        String sql = insert.getSQL();
+        update(sql);
+    }
+    public static ResultSet select(List<String> columns, String table, Map<String,String> limits, int startRow, int endRow) throws Exception {
+        Select select = new Select(columns,table,limits,startRow,endRow);
+        String sql = select.getSQL();
+        return query(sql);
+    }
+    public static void update(String table, Map<String,String> vMap, Map<String,String> limits) throws GExcptSQL {
+        Update update = new Update(table,vMap,limits);
+        String sql = update.getSQL();
+        update(sql);
+    }
     public static ResultSet query(String sql) throws Exception {
         if(!ifInit) return null;
         ResultSet rs = null;
diff --git a/src/dao/Delete.java b/src/dao/Delete.java
new file mode 100644
index 0000000..c52666a
--- /dev/null
+++ b/src/dao/Delete.java
@@ -0,0 +1,31 @@
+package dao;
+
+import java.util.Map;
+
+public class Delete extends SQLStmt {
+    private static final String fs = "DELETE ";
+    private Map<String,String> limits;
+
+    Delete(String table, Map<String, String> limits) {
+        super(table);
+        this.setLimits(limits);
+    }
+    @Override
+    public String getSQL() {
+        return this.getFs()+this.getLs();
+    }
+    private String getLs(){
+        return dao.Utils.whereAnd(this.getLimits());
+    }
+    public String getFs(){
+        return fs+this.getTable()+" ";
+    }
+
+    private Map<String, String> getLimits() {
+        return limits;
+    }
+
+    private void setLimits(Map<String, String> limits) {
+        this.limits = limits;
+    }
+}
diff --git a/src/dao/Insert.java b/src/dao/Insert.java
new file mode 100644
index 0000000..4135bd6
--- /dev/null
+++ b/src/dao/Insert.java
@@ -0,0 +1,43 @@
+package dao;
+
+import utils.Utils;
+
+import java.util.Map;
+
+public class Insert extends SQLStmt {
+    private static final String fs ="INSERT INTO ";
+    private Map<String, String> vMap;
+    Insert(String table, Map<String, String> vMap){
+        super(table);
+        this.setVMap(vMap);
+    }
+    @Override
+    public String getSQL() {
+        return this.getFs()+this.getVs();
+    }
+
+    @Override
+    public String getFs() {
+        return fs+this.getTable()+" ";
+    }
+    private String getVs(){
+        StringBuilder sql = new StringBuilder("(");
+        for(String key: this.getVMap().keySet()){
+            sql.append(key).append(", ");
+        }
+        sql = new StringBuilder(Utils.cutTail(sql.toString(), 2) + ") ");
+        sql.append("VALUES (\'");
+        for(String value: vMap.values()){
+            sql.append(value).append("\', \'");
+        }
+        sql = new StringBuilder(Utils.cutTail(sql.toString(), 3) + ")");
+        return sql.toString();
+    }
+    private Map<String, String> getVMap() {
+        return vMap;
+    }
+
+    private void setVMap(Map<String, String> vMap) {
+        this.vMap = vMap;
+    }
+}
diff --git a/src/dao/SQLStmt.java b/src/dao/SQLStmt.java
new file mode 100644
index 0000000..61f653f
--- /dev/null
+++ b/src/dao/SQLStmt.java
@@ -0,0 +1,16 @@
+package dao;
+
+public abstract class SQLStmt {
+    private String table;
+    SQLStmt(String table) {
+        this.setTable(table);
+    }
+    public abstract String getSQL();
+    public abstract String getFs();
+    String getTable() {
+        return table;
+    }
+    public void setTable(String table) {
+        this.table = table;
+    }
+}
diff --git a/src/dao/Select.java b/src/dao/Select.java
new file mode 100644
index 0000000..472cd12
--- /dev/null
+++ b/src/dao/Select.java
@@ -0,0 +1,62 @@
+package dao;
+
+import java.util.List;
+import java.util.Map;
+
+public class Select extends SQLStmt {
+    private static final String fs ="SELECT ";
+    private Map<String,String> limits;
+    private List<String> columns;
+    private int startRow;
+    private int endRow;
+    public Select(List<String> columns, String table, Map<String,String> limits, int startRow, int endRow){
+        super(table);
+        this.setColumns(columns);
+        this.setLimits(limits);
+        this.setStartRow(startRow);
+        this.setEndRow(endRow);
+    }
+    @Override
+    public String getSQL() {
+        return this.getFs()+this.getTs()+this.getLs();
+    }
+    private String getLs(){
+        String sql = dao.Utils.whereAnd(this.getLimits())+" ";
+        sql+="LIMIT "+this.getStartRow()+", "+this.getEndRow();
+        return sql;
+    }
+    @Override
+    public String getFs() {
+        return fs+dao.Utils.linkColumn(this.getColumns())+" ";
+    }
+    private String getTs(){
+        return "FROM "+this.getTable()+" ";
+    }
+    private Map<String, String> getLimits() {
+        return limits;
+    }
+    public void setLimits(Map<String, String> limits) {
+        this.limits = limits;
+    }
+    private List<String> getColumns() {
+        return columns;
+    }
+    public void setColumns(List<String> columns) {
+        this.columns = columns;
+    }
+    private int getStartRow() {
+        return startRow;
+    }
+
+    private void setStartRow(int startRow) {
+        this.startRow = startRow;
+    }
+
+    private int getEndRow() {
+        return endRow;
+    }
+
+    private void setEndRow(int endRow) {
+        this.endRow = endRow;
+    }
+}
diff --git a/src/dao/Update.java b/src/dao/Update.java
new file mode 100644
index 0000000..20f9f88
--- /dev/null
+++ b/src/dao/Update.java
@@ -0,0 +1,52 @@
+package dao;
+
+import java.util.Map;
+
+public class Update extends SQLStmt {
+    private static final String fs ="UPDATE ";
+    private Map<String,String> limits;
+    private Map<String,String> vMap;
+
+
+    Update(String table, Map<String, String> vMap, Map<String, String> limits) {
+        super(table);
+        this.setVMap(vMap);
+        this.setLimits(limits);
+    }
+
+    @Override
+    public String getSQL() {
+        return this.getFs()+this.getVs()+this.getLs();
+    }
+
+    @Override
+    public String getFs() {
+        return fs+this.getTable()+" ";
+    }
+    private String getLs(){
+        return dao.Utils.whereAnd(this.getLimits());
+    }
+    private String getVs(){
+        String sql = "SET ";
+        sql+=Utils.linkColumn(Utils.linkKeyValue(this.getVMap()))+" ";
+        return sql;
+    }
+
+
+    private Map<String, String> getLimits() {
+        return limits;
+    }
+
+    public void setLimits(Map<String, String> limits) {
+        this.limits = limits;
+    }
+    public Map<String, String> getVMap() {
+        return vMap;
+    }
+
+    public void setVMap(Map<String, String> vMap) {
+        this.vMap = vMap;
+    }
+
+
+}
diff --git a/src/dao/Utils.java b/src/dao/Utils.java
index 8f22aa1..309bc7c 100644
--- a/src/dao/Utils.java
+++ b/src/dao/Utils.java
@@ -1,6 +1,33 @@
 package dao;
 
-public interface Utils {
-
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
 
+public interface Utils {
+    static String whereAnd(Map<String,String> map){
+        List<String> list = linkKeyValue(map);
+        String sql = "WHERE ";
+        for(String s:list){
+            sql+=s+" AND ";
+        }
+        sql = utils.Utils.cutTail(sql,5)+"";
+        return sql;
+    }
+    //with ", "
+    static String linkColumn(List<String> list){
+        String sql = "";
+        for(String c:list){
+            sql+=c+", ";
+        }
+        return utils.Utils.cutTail(sql,2);
+    }
+    //with " = "
+    static List<String> linkKeyValue(Map<String, String> map){
+        List<String> list = new ArrayList<>();
+        for(Map.Entry<String,String> entry:map.entrySet()){
+            list.add(entry.getKey()+" = \'"+entry.getValue()+"\'");
+        }
+        return list;
+    }
 }
diff --git a/src/utils/Utils.java b/src/utils/Utils.java
index a1c7c56..d439588 100644
--- a/src/utils/Utils.java
+++ b/src/utils/Utils.java
@@ -5,24 +5,26 @@ import java.util.List;
 import java.util.Map;
 
 public interface Utils {
-    public static Map<String,Integer> userAttrNum =new HashMap<>()
-
+    Map<String,Integer> userAttrNum =new HashMap<>()
     {
             {
-                userAttrNum.put("administrator",5);
-                userAttrNum.put("student",7);
-                userAttrNum.put("teacher",8);
+                put("administrator",5);
+                put("student",7);
+                put("teacher",8);
             }
     };
-    public static String toUpperFirstChar(String string) {
+    static String toUpperFirstChar(String string) {
         char[] charArray = string.toCharArray();
         charArray[0] -= 32;
         return String.valueOf(charArray);
     }
-    public static List<String> formatUserInfo(String userType, List<String> userInfo){
+    static List<String> formatUserInfo(String userType, List<String> userInfo){
         for(int i=0;i<userAttrNum.get(userType)-userInfo.size();i++){
             userInfo.add("");
         }
         return userInfo;
     }
+    static String cutTail(String s,int i){
+        return s.substring(0,s.length()-i);
+    }
 }