diff --git a/CS体系结构-记账系统/DatabaseHelper.java b/CS体系结构-记账系统/DatabaseHelper.java
new file mode 100644
index 0000000..f835237
--- /dev/null
+++ b/CS体系结构-记账系统/DatabaseHelper.java
@@ -0,0 +1,64 @@
+package com.example.account_book;
+
+import android.content.ContentValues;
+import android.content.Context;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+
+import androidx.annotation.Nullable;
+
+public class DatabaseHelper extends SQLiteOpenHelper {
+
+    public static final String COST_MONEY = "cost_money";
+    public static final String COST_DATE = "cost_date";
+    public static final String COST_TITLE = "cost_title";
+    public static final String ACCOUNT_COST = "account_cost";
+
+    SQLiteDatabase mdatabaseHelper;
+
+    public DatabaseHelper(@Nullable Context context) {
+        super(context, "account_book", null, 1);
+    }
+
+    @Override
+    public void onCreate(SQLiteDatabase db) {
+        db.execSQL("create table if not exists account_cost(" +
+                "id integer primary key, "+
+                "cost_title varchar, "+
+                "cost_date varchar, "+
+                "cost_money varchar)");
+
+    }
+
+    public void insertCost(CostBean costBean){  //增添
+        SQLiteDatabase database = getWritableDatabase();
+        ContentValues cv = new ContentValues();
+        cv.put(COST_TITLE, costBean.costTitle);
+        cv.put(COST_DATE, costBean.costDate);
+        cv.put(COST_MONEY, costBean.costMoney);
+        database.insert(ACCOUNT_COST, null, cv);
+    }
+
+    public Cursor getAllCostData(){    //查询
+        SQLiteDatabase database = getWritableDatabase();
+        return database.query(ACCOUNT_COST,null,null,null,null,null,COST_DATE + " ASC");
+    }
+
+    public void deleteAllData(){ //删除
+        SQLiteDatabase database = getWritableDatabase();
+        database.delete(ACCOUNT_COST,null,null);
+    }
+
+    public void toDelete(CostBean costBean){
+        SQLiteDatabase database = getWritableDatabase();
+        database.delete(ACCOUNT_COST,"COST_TITLE = ? and COST_MONEY = ? and COST_DATE = ?",
+                new String[]{""+costBean.costTitle,""+costBean.costMoney,""+costBean.costDate});
+    }
+
+    @Override
+    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+
+    }
+
+}