Android 如何在同一个SQLite数据库的不同表中保存两组信息？

我正在开发一个预算应用程序，我想请用户添加收入和支出，然后我想在概览活动中获得这两组数据的总和。我在网上进行了研究，发现将这些值放在两个不同的表中是最好的方法。（如果你有任何其他想法，请告诉我。）
我如何将收入和支出放在不同的表格上，然后如何将它们联系起来以获得总额？
我已将费用数据保存在一个表中，但不知道如何制作另一个收入表。请原谅我不知道最好的方法，因为我对使用SQLite还不熟悉

添加费用。java

import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.Toast;



public class add_expense extends AppCompatActivity {

    DatabaseHelper myDbexpense;
    EditText editAmountexpense, editDateexpense, editNotesexpense;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_expense);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_expense);
        setSupportActionBar(toolbar);
        getSupportActionBar().setTitle("Add Expense");
        toolbar.setNavigationIcon(getResources().getDrawable(R.drawable.ic_back));
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        myDbexpense = new DatabaseHelper(this);

        editAmountexpense = (EditText) findViewById(R.id.amount_expense);
        editDateexpense = (EditText) findViewById(R.id.date_expense);
        editNotesexpense = (EditText) findViewById(R.id.notes_expense);
        AddData();


        Spinner spinner;
        ArrayAdapter<CharSequence> adapter;

        spinner = (Spinner) findViewById(R.id.categorydropdown_expense);
        adapter = ArrayAdapter.createFromResource(this, R.array.expensecategory_array, android.R.layout.simple_spinner_item);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(getBaseContext(), parent.getItemAtPosition(position) + " selected as category", Toast.LENGTH_LONG).show();
            }

            @Override
            public void onNothingSelected(AdapterView<?> parent) {

            }
        });

        toolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                onBackPressed();
            }
        });

    }

    public void AddData(){
            FloatingActionButton fab2 = (FloatingActionButton) findViewById(R.id.fab_tick_expense);
            fab2.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    boolean isInserted;
                    if (myDbexpense.insertData(
                            editAmountexpense.getText().toString(),
                            editDateexpense.getText().toString(),
                            editNotesexpense.getText().toString())) {
                        isInserted = true;
                        Intent intent=new Intent(add_expense.this,MainActivity.class);
                        startActivity(intent);
                    }
                    else isInserted = false;
                    if(isInserted == true)
                        Toast.makeText(add_expense.this,"Data Inserted",Toast.LENGTH_LONG).show();
                    else
                        Toast.makeText(add_expense.this,"Data not Inserted",Toast.LENGTH_LONG).show();
                }
            });

        }
    }

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.view.View;

public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String TAG = "DatabaseHelper";

    public static final String DATABASE_NAME = "expense.db";
    public static final String TABLE_NAME = "expense_table";
    public static final String COL_1 = "ID";
    public static final String COL_2 = "AMOUNT";
    public static final String COL_3 = "DATE";
    public static final String COL_4 = "NOTES";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 3);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT,AMOUNT INTEGER,DATE INTEGER,NOTES TEXT)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }

    public boolean insertData(String amount, String date, String notes) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(COL_2, amount);
        contentValues.put(COL_3, date);
        contentValues.put(COL_4, notes);
        long result = db.insert(TABLE_NAME, null, contentValues);
        if (result == -1)
            return false;
        else
            return true;
    }

    public Cursor getData() {
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor res = db.rawQuery("select * from " + TABLE_NAME, null);
        return res;
    }

    public Cursor getItemID(String name){
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "SELECT " + COL_1 + " FROM " + TABLE_NAME + " WHERE " + COL_2 + " = '" + name + "'";
        Cursor data = db.rawQuery(query, null);
        return data;
    }

    public boolean updateData(String id, String amount, String date, String notes) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put(COL_1, id);
        contentValues.put(COL_2, amount);
        contentValues.put(COL_3, date);
        contentValues.put(COL_4, notes);
        db.update(TABLE_NAME, contentValues, "ID = ?", new String[]{id});
        return true;
    }

    public Integer deleteData(String id) {
        SQLiteDatabase db = this.getWritableDatabase();
        return db.delete(TABLE_NAME, "ID = ?", new String[]{id});
    }


}

---

在

DatabaseHelper

类的

onCreate

方法中创建两个表，并相应地处理插入/读取。或者，如果要使用单个表，请使用负值表示支出，正值表示收入

有很多方法可以解决这个问题。您只需要设计并决定如何实现它