Question

在我的应用程序中，我使用sqlit数据库存储用户信息，并且这些信息存储成功，但是它们存储了2天，因为我可以在2天内检索它们并在屏幕上显示但是在2天或更长时间之后当我运行我的应用程序没有显示数据“我调试我的代码时返回的光标是空的”我使用DataBaseAdapter和DatabaseHelper类来创建数据库，我真的很想知道，为什么会出现这个问题？我怎么解决呢？我相信代码中没有问题，因为我可以插入和检索数据，我在数据/数据/我的pavkage名称/ databases / DBname中找到了我的数据库

任何机构都对这个问题有所了解？请帮帮我......

这是我创建数据库的代码

public class DBAdapter
 {
public static final String DB_NAME="MYDB";
private static final int DB_VERSION=5;
private static final String TRACKER_TABLE_NAME="Tracker";
private static final String EXERCISE_TABLE_NAME="Exercise";
private static final String MEAL_TABLE_NAME="Meal";
private static final String FOOD_TABLE_NAME="Food";
private static final String MEALFOOD_TABLE_NAME="MealFood";

private static final String TAG = "DBAdapter";

private DatabaseHelper DBHelper;
private SQLiteDatabase db;
private Context context;

// table Exercise columns name
public static final String KEY_DATE="Date";
public static final String KEY_TIME="Time";
public static final String KEY_NAME="Name";
public static final String KEY_PERIOD="Period";
public static final String KEY_BURNEDCALS="Burned_Calories";

// table Tracker columns Name
public static final String KEY_TDATE="Date";
public static final String KEY_DAILY_BCALS_COUNTER="DialyBCalsCounter";
public static final String KEY_DAILY_NCALS_COUNTER="DialyNCalsCounter";
public static final String KEY_VB12_COUNTER="VB12Counter";
public static final String KEY_PROTEIN_COUNTER="ProteinCounter";
public static final String KEY_SODIUM_COUNTER="SodiumCounter";
public static final String KEY_IRON_COUNTER="IronCounter";
public static final String KEY_CHOLESTEROL_COUNTER="CholesterolCounter";
public static final String KEY_FAT_SAT_COUNTER="FatSatCounter";
public static final String KEY_FAT_MONO_COUNTER="FatMonoCounter";

// table Meal columns Name
public static final String KEY_MDATE="Date";
public static final String KEY_MTIME="Time";
public static final String KEY_MEALTYPE="MealType";

// table Food columns Name
public static final String KEY_FOODID="Food_ID";
public static final String KEY_FOODNAME="Food_Name";
public static final String KEY_CALORIES="Calories";
public static final String KEY_VB12="VB12";
public static final String KEY_CHOLESTEROL="Cholesterol";
public static final String KEY_PROTEIN="Protein";
public static final String KEY_IRON="Iron";
public static final String KEY_SODIUM="Sodium";
public static final String KEY_FAT_MONO="Fat_Mono";
public static final String KEY_FAT_Sat="Fat_Sat";
public static final String KEY_CARBOHYDRATE="carbohydrate";

// table MealFood columns Name
public static final String KEY_MFDATE="Date";
public static final String KEY_MFTIME="Time";
public static final String KEY_MFMEALTYPE="MealType";
public static final String KEY_MFFOODID="Food_ID";


private static final String EXERCISE_TABLE_CREATE ="create table Exercise (Date text not null  , "+
        "Time  text not null  ,Name  text not null," + " Period  REAL not null, Burned_Calories  REAL  not null," +
        " primary key(Date,Time ) );"  ;

private static final String Meal_TABLE_CREATE= "create table IF NOT EXISTS Meal (Date  text not null , "+
        "Time   text not null,MealType  text not null,"+ " primary key(Date,Time ,MealType) );" ;

private static final String FOOD_TABLE_CREATE= "create table IF NOT EXISTS Food (Food_ID  INTEGER  primary key  AUTOINCREMENT  , "+
        "Food_Name   text not null,Calories  integer  not null,"+ "VB12   integer  not null,Cholesterol  integer  not null,"+ 
        "Protein   integer  not null,Iron integer  not null,Sodium integer  not null,Fat_Mono integer  not null,Fat_Sat integer  not null,carbohydrate integer  not null);" ;

private static final String MealFOOD_TABLE_CREATE= "create table IF NOT EXISTS MealFood (Date  text  not null , "+
        "Time   text not null,MealType  text not null,"+"Food_ID  integer   not null ,  primary key(Date,Time ,MealType,Food_ID) );" ;

private static final String TRACKER_TABLE_CREATE= "create table IF NOT EXISTS Tracker (Date  text   not null  primary key  , "+
        "DialyBCalsCounter integer  not null,DialyNCalsCounter  integer  not null,"+ 
        "VB12Counter   integer  not null,ProteinCounter  integer  not null,"+ "SodiumCounter  integer  not null,IronCounter integer  not null,"+
        "CholesterolCounter  integer  not null );" ;    

 public DBAdapter(Context ctxt)
    {
    this.context=ctxt;
    DBHelper= new DatabaseHelper(context);
       }

private static class DatabaseHelper extends SQLiteOpenHelper
{
    DatabaseHelper(Context    context)
    {
        super(context, DB_NAME, null, DB_VERSION);
    }

    public void onCreate(SQLiteDatabase db)
    {
        try
        {
            db.execSQL(EXERCISE_TABLE_CREATE);
            db.execSQL(TRACKER_TABLE_CREATE);
            db.execSQL(Meal_TABLE_CREATE);
            db.execSQL(FOOD_TABLE_CREATE);
            db.execSQL(MealFOOD_TABLE_CREATE);
        }
        catch(SQLException e)
        {
            e.printStackTrace();
        }
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
    {
        //          Log.w(TAG, "Upgrading database from version" + oldVersion +" to "+ newVersion + ", which will destroy all old data");     
        //          db.execSQL("DROP TABLE IF EXISTS Exercise");
        //          db.execSQL("DROP TABLE IF EXISTS Food");
        //          db.execSQL("DROP TABLE IF EXISTS Meal");
        //          db.execSQL("DROP TABLE IF EXISTS MealFood");
        //          
        //          onCreate(db);
    }
}   

//--open the DB
public DBAdapter open() throws SQLException
{
    db = DBHelper.getWritableDatabase();
    return this;
}

//---closes the database---
public void close()
{
    DBHelper.close();
}
//---insert   Exercise info to the Exercise table---
public long SaveExecise(String date ,String  time,String name ,float  period, float BurnedCalories)
{
    ContentValues content = new ContentValues();
    content.put(KEY_DATE, date);
    content.put(KEY_TIME, time);
    content.put(KEY_NAME, name);
    content.put(KEY_PERIOD,period);
    content.put(KEY_BURNEDCALS, BurnedCalories);

    return db.insert(EXERCISE_TABLE_NAME, null, content);
}       

// retrieve  ex_Name  ,ex_period, ex_burned cals of all exercises played in a specific date  
public Cursor getExerciseInfo(String  date) throws SQLException
{
    Cursor  C_excer = db.query(EXERCISE_TABLE_NAME, new String[] {KEY_NAME,KEY_PERIOD,KEY_BURNEDCALS},
            KEY_DATE + " = '" + date + "'", null, null, null, null);
    //if (C_excer != null) {
    C_excer.moveToFirst();
    //}
    return C_excer;
}

// insert meal info to the meal table 
public long SaveMeal(String date , String time , String mealType)
{
    ContentValues content = new ContentValues();
    content.put(KEY_MDATE,date);
    content.put(KEY_MTIME,time);
    content.put(KEY_MEALTYPE,mealType);
    return db.insert(MEAL_TABLE_NAME, null, content);

}

// insert Food info to the Food table 
public long SaveFood(String name,int calories,int Vit_B12,int cholesterol,int protein ,int iron ,int sodium,int Fat_Mono,int Fat_Sat,int carbohydrate)
{
    ContentValues content = new ContentValues();

    content.put(KEY_FOODNAME,name);
    content.put(KEY_CALORIES,calories);
    content.put(KEY_VB12,Vit_B12);
    content.put(KEY_CHOLESTEROL,cholesterol);
    content.put(KEY_PROTEIN,protein);
    content.put(KEY_IRON,iron);
    content.put(KEY_SODIUM,sodium);
    content.put(KEY_FAT_MONO,Fat_Mono);
    content.put(KEY_FAT_Sat,Fat_Sat);
    content.put(KEY_CARBOHYDRATE,carbohydrate);


    return db.insert(FOOD_TABLE_NAME, null, content);

}

// get food id by its name   

public int getFoodIDByName(String name) throws SQLException
{    int id =0;
Cursor cursor=db.query(true,FOOD_TABLE_NAME, new String[]{KEY_FOODID},  KEY_FOODNAME+ " = '" + name + "'", null, null, null, null,null);
if (cursor != null) {
    cursor.moveToLast();

    id=cursor.getInt(cursor.getColumnIndex(KEY_FOODID));

}
cursor.close();
cursor.deactivate();
return id;

}


// insert mealFood info  to mealFood table 
public long SaveMealFood(String date , String time , String mealType, int Food_id)
{
    ContentValues content = new ContentValues();
    content.put(KEY_MFDATE,date);
    content.put(KEY_MFTIME,time);
    content.put(KEY_MFMEALTYPE,mealType);
    content.put(KEY_MFFOODID,Food_id);
    return db.insert(MEALFOOD_TABLE_NAME, null, content);
}
// get  specific meal foodID from mealFood table
public Cursor  getSpecificMealFoodsID(String date,String mealType) throws SQLException
{
    Cursor cursor=db.query(true,MEALFOOD_TABLE_NAME, new String[]{KEY_MFFOODID},KEY_MFDATE+ " = '" + date + "'"+ " "+ "and" +" "+ KEY_MFMEALTYPE+ " = '" + mealType + "'", null, null, null, null,null);
    if (cursor != null) {
        cursor.moveToFirst();
    }
    return cursor;

}



//get food name,cals from food table based on the food id that we get it from the mealFood table    
public Cursor  getFoodNameAndCals(int food_id) throws SQLException
{
    Cursor cursor=db.query(true,FOOD_TABLE_NAME, new String[]{KEY_FOODNAME,KEY_CALORIES},KEY_FOODID+"="+food_id, null, null, null, null,null);
    if (cursor != null) {
        cursor.moveToFirst();
    }

    return cursor;


}




public Cursor getAllFoods() throws SQLException
{ 
    Cursor food_Cursor = db.query(FOOD_TABLE_NAME, new String[] {KEY_FOODID, KEY_FOODNAME,KEY_CALORIES}, null, null, null, null, null);
    if (food_Cursor  != null) {
        food_Cursor .moveToFirst();
    }
    return food_Cursor ;
}

// retrieve all store exercises // for testing 
public Cursor getExerciseInfo() throws SQLException
{
Cursor  C_excer = db.query(EXERCISE_TABLE_NAME, new String[] 
      {              
         KEY_NAME,KEY_PERIOD,KEY_BURNEDCALS},null, null, null, null, null);
    //if (C_excer != null) {
    C_excer.moveToFirst();
    //}
 return C_excer;}
}

在我的应用程序活动中，我只使用了插入和检索数据的方法我应该做什么来防止每次运行应用程序时重新创建数据库？既然我认为你说的是真的，请帮帮我

Answer 1

我发现您的代码没有任何问题。您的onUpgrade方法中的代码是否始终被注释掉了？

我的猜测是你增加了数据库版本，这会触发onUpgrade方法并删除你的表然后重新创建它们（假设代码并不总是被注释掉）。

数据存储在我的sqlite数据库中只有几天了？

1 个答案: