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在我的应用程序中，我使用 sqlit 数据库来存储用户信息，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 天内检索它们并将它们显示在屏幕上，但是在我运行 2 天或更长时间之后我的应用程序没有显示数据“调试代码时返回的光标为空”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？我该如何解决？
我相信代码没有问题，因为我可以插入和检索数据，并且我在 data/data/my pavkage name /databases/ DBname 中找到了我的数据库

有没有人知道这个问题？请帮我 ......

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，我只是使用了插入和检索数据的方法，我应该怎么做才能防止在每次运行应用程序时重新创建数据库？因为我认为你说的是​​真的，请帮助我

4

1 回答 1

0

我认为您的代码没有任何问题。您的方法中的代码是否onUpgrade总是被注释掉？

我的猜测是您增加了数据库版本，这触发了该onUpgrade方法并删除了您的表，然后重新创建了它们（假设该代码并不总是被注释掉）。

于 2012-05-31T13:34:30.317 回答