在 Sqlite 中仅创建和更新单个值

Question

我想在我的Database 中创建一个新表（这意味着我将有两个表）。在该表中，我将只有一个且唯一的值，并且该唯一值的使用是我将得到它，我将执行加法或减法并再次插入/更新它以获取已减去或添加值的新值（基本上它是 integer 值或 boolean 用于小数）。我还是 sqlite 的新手，也是 android 开发的初学者。

我的问题是，我将如何在表中按默认设置/插入一个值，以及如何获取和更新它。因为当我在活动本身或按钮/工厂中添加INSERT 查询时，每次我打开片段本身或按下按钮/工厂时，它都会添加新值。我将如何在默认情况下只有一个数据以及如何获取它，以便我可以在其中添加或减去值并更新它以获得新值？

我创建了两个表：

@Override
    public void onCreate(SQLiteDatabase db) {
        final String SQL_CREATE_CASHFLOW_TABLE = "CREATE TABLE " + ItemEntry.TABLE_NAME2 + " (" +
                ItemEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                ItemEntry.COLUMN_INCOME + " INTEGER NOT NULL, " +
                ItemEntry.COLUMN_SAVINGS + " INTEGER NOT NULL " +
                ");";

        final String SQL_CREATE_ITEMLIST_TABLE = "CREATE TABLE " + ItemEntry.TABLE_NAME + " (" +
                ItemEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                ItemEntry.COLUMN_LABEL + " TEXT NOT NULL, " +
                ItemEntry.COLUMN_DETAIL + " TEXT, " +
                ItemEntry.COLUMN_AMOUNT + " INTEGER NOT NULL, " +
                ItemEntry.COLUMN_DATE + " TEXT " +
                ");";

        db.execSQL(SQL_CREATE_ITEMLIST_TABLE);
        db.execSQL(SQL_CREATE_CASHFLOW_TABLE);
    }

我从 bk7 尝试过的代码：

public void insertOrUpdateTheIncomeAndSavings(int income, int savings){
        SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();

        Cursor cursor = sqLiteDatabase.rawQuery("SELECT * from "+ItemEntry.TABLE_NAME2,null);
        if(cursor.moveToNext()){
            //update the values of first row here

            //update income
            Cursor cursor2 = sqLiteDatabase.rawQuery("UPDATE "+ItemEntry.TABLE_NAME2+" SET "+ItemEntry.COLUMN_INCOME+
                    " = "+ income + " WHERE "+ItemEntry._ID +" = 1",null);

        }else{
            //insert the value here
            ContentValues cv = new ContentValues();
            cv.put(ItemEntry.COLUMN_INCOME, 0);
            cv.put(ItemEntry.COLUMN_SAVINGS, 0);
        }

        if(cursor!=null){
            cursor.close();
        }
        sqLiteDatabase.close();

    }

如何在收入 java 中做到这一点：

package com.example.admin.test2;


import android.content.Context;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;


/**
 * A simple {@link Fragment} subclass.
 */
public class Income extends Fragment {

    public Income() {
        // Required empty public constructor
    }

    private EditText textInput;
    private FloatingActionButton fabPlus;
    private FloatingActionButton fabMinus;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view =  inflater.inflate (R.layout.fragment_income, container, false);

        textInput = (EditText) view.findViewById(R.id.editText2);
        fabPlus = (FloatingActionButton) view.findViewById(R.id.fabPlus);
        fabMinus = (FloatingActionButton) view.findViewById(R.id.fabMinus);

        fabPlus.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            }
        });
        return view;
    }
}

并从此editText获取值：

textInput = (EditText) view.findViewById(R.id.editText2);

我想在这个textView中显示我在数据库中输入的输入，但是它不起作用..请检查代码：

public void getIncome() {
        Cursor cur = mDatabase.rawQuery("SELECT " + ItemContract.ItemEntry.COLUMN_INCOME + " as Income FROM " + ItemContract.ItemEntry.TABLE_NAME2
                , null);

        if (cur.moveToFirst()) {

            int incomeTotal = cur.getInt(cur.getColumnIndex("Income"));// get final total
            income.setText("₱ " + incomeTotal);
        }

Answer 1

如果第一行不存在则插入第一行，如果存在则更新第一行。

     public void insertOrUpdateTheIncomeAndSavings(int income, int savings){
            SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();

          Cursor cursor = sqLiteDatabase.rawQuery("select * from "+ItemEntry.TABLE_NAME2,null);
            if(cursor.moveToNext()){
            //update the values of first row here

            }else{
                //insert the value here
            }

            if(cursor!=null){
            cursor.close();
            }
           sqLiteDatabase.close();

        }

编辑：在 Onclick 中添加这个

 DBHelper dbhelper = new DBHelper(getActivity());
  int income = Integer.valueOf(incomeEditText.getText().toString());
  int savings = Integer.valueOf(savingsEditText.getText().toString());
  dbhelper.insertOrUpdateTheIncomeAndSavings(income,savings);  

Answer 2

public void updateEmployeeName(String empNo,String new_empname) {
    Cursor cursor = null;
    String empName = "";
    try {
        cursor = SQLiteDatabaseInstance_.rawQuery("SELECT EmployeeName 
        FROM Employee WHERE EmpNo=?", new String[] {empNo + ""});
        if(cursor.getCount() > 0) {
            cursor.moveToFirst();
            empName = cursor.getString(cursor.getColumnIndex("EmployeeName"));
            update(empname);
        }else{
            update(new_empname);
        } 
      }finally {
        cursor.close();
     }
 }    

**Update single value use this query:-**
    public void update(){
    ContentValues cv = new ContentValues();
    cv.put(ColumnName, newValue);
    db.update(TABLE_NAME, cv, Column + "= ?", new String[] {rowId});
}

    **delete single value use this query:-**

    public void delete_singlevalue(String newValue) {
            SQLiteDatabase db = getWritableDatabase();          
            db.execSQL("delete from TABLE_NAME where 
            ColumnName="+"'"+newValue+"'");
            db.close();   
      }