przykładowy program SQL w Androidzie

Question

Jestem Newbee do koncepcji bazy danych specjalnie potrzebuję względne koncepcje bazy danych .. Chcę przykład pracy, która używa bazy danych sqlite dla Androida..i chodził przez android strony programisty, ale znaleziono bardzo mało rzeczy dotyczących przykładów bazy danych. Ponieważ jestem nowy w koncepcjach baz danych Czy ktoś może zaproponować mi jakieś dobre zasoby do zrozumienia create(), insert(), Query() ... etc ... i byłoby lepiej, gdybym otrzymał przykładowy program pracujący z Androidem. .

góry dzięki

Answer 1

to bardzo prosty w poniższy kod ... utworzyć 3 klasy o nazwie na przykład - 1. użyłem Interfejs stałe, patrz pełny kod i znaleźć to wykorzystać

  package com.mypackage.quaddeals; 

import android.net.Uri; 
import android.provider.BaseColumns; 

public interface Constants extends BaseColumns { 
    public static final String TABLE_NAME = "user_deal"; 

    public static final String AUTHORITY = "com.mypackage.quaddeals"; 
    public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY 
      + "/" + TABLE_NAME); 

    public static final String TITLE = "title"; 
    public static final String CITYID = "cityid"; 

} 

2.BruPress klasy danych ...

package com.mypackage.quaddeals; 

import static android.provider.BaseColumns._ID; 

import static com.mypackage.quaddeals.Constants.CITYID; 
import static com.mypackage.quaddeals.Constants.TITLE; 
import static com.mypackage.quaddeals.Constants.TABLE_NAME; 

import android.content.Context; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.util.Log; 

public class Bru_Press_Data extends SQLiteOpenHelper { 
    public static final String DATABASE_NAME = "QuadDeals.db"; 
    public static final int DATABASE_VERSION = 1; 

    /** Create a helper object for the Events database */ 
    public Bru_Press_Data(Context ctx) { 
     super(ctx, DATABASE_NAME, null, DATABASE_VERSION); 

    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     try { 
      db.execSQL("CREATE TABLE " + TABLE_NAME + " (" + _ID 
        + " INTEGER PRIMARY KEY AUTOINCREMENT," + TITLE 
        + " TEXT UNIQUE," + CITYID + " TEXT);");    
     } catch (Exception e) { 
      Log.v("Bru_Press_Data", "exception in table created"); 
     } 
    } 
    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME); 
     onCreate(db); 
    } 

} 

klasy 3.Provider

package com.mypackage.quaddeals; 

import static android.provider.BaseColumns._ID; 

import static com.mypackage.quaddeals.Constants.CONTENT_URI; 
import static com.mypackage.quaddeals.Constants.AUTHORITY; 
import static com.mypackage.quaddeals.Constants.TABLE_NAME; 

import android.app.SearchManager; 
import android.content.ContentProvider; 
import android.content.ContentUris; 
import android.content.ContentValues; 
import android.content.UriMatcher; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.net.Uri; 
import android.text.TextUtils; 
import android.util.Log; 

public class Bru_Press_Provider extends ContentProvider { 
    private static final int QUADUSER = 1; 
    private static final int QUADUSER_ID = 2; 
    /** The MIME type of a directory of events */ 
    private static final String CONTENT_TYPE = "vnd.android.cursor.dir/vnd.example.brown"; 

    /** The MIME type of a single event */ 
    private static final String CONTENT_ITEM_TYPE = "vnd.android.cursor.item/vnd.example.brown"; 
    private static final String CONTENT_TYPE1 = "vnd.android.cursor.dir/vnd.example.brown"; 

    /** The MIME type of a single event */ 
    private static final String CONTENT_ITEM_TYPE1 = "vnd.android.cursor.item/vnd.example.brown"; 
// private static final String CONTENT_TYPE2 = "vnd.android.cursor.dir/vnd.example.brown"; 

    /** The MIME type of a single event */ 
// private static final String CONTENT_ITEM_TYPE2 = "vnd.android.cursor.item/vnd.example.brown"; 
    private Bru_Press_Data news; 
    private UriMatcher uriMatcher; 

    private Cursor cursor; 
    private SQLiteDatabase db; 
    String[] str; 

    @Override 
    public boolean onCreate() { 

     uriMatcher = new UriMatcher(UriMatcher.NO_MATCH); 
     uriMatcher.addURI(AUTHORITY, "user_deal", QUADUSER); 
     uriMatcher.addURI(AUTHORITY, "user_deal/#", QUADUSER_ID); 

     news = new Bru_Press_Data(getContext()); 
     return true; 
    } 

    @Override 
    public Cursor query(Uri uri, String[] projection, String selection, 
      String[] selectionArgs, String orderBy) { 
     SQLiteDatabase db; 
     Cursor cursor = null; 
     if (uriMatcher.match(uri) == QUADUSER_ID) { 
      long id = Long.parseLong(uri.getPathSegments().get(1)); 
      selection = appendRowId(selection, id); 
     } 
     if (uriMatcher.match(uri) == QUADUSER) { 
      // Get the database and run the query 
      db = news.getReadableDatabase(); 
      cursor = db.query(TABLE_NAME, projection, selection, selectionArgs, 
        null, null, orderBy); 
     } 
     cursor.setNotificationUri(getContext().getContentResolver(), uri); 
     return cursor; 
    } 

    @Override 
    public String getType(Uri uri) { 
     switch (uriMatcher.match(uri)) { 
     case QUADUSER: 
      return CONTENT_TYPE; 
     case QUADUSER_ID: 
      return CONTENT_ITEM_TYPE; 
     default: 
      throw new IllegalArgumentException("Unknown URI " + uri); 
     } 
    } 

    @Override 
    public Uri insert(Uri uri, ContentValues values) { 

     SQLiteDatabase db = news.getWritableDatabase(); 
     Uri newUri = null; 
     long id = -1; 
     // Validate the requested uri 

     if (uriMatcher.match(uri) == QUADUSER) { 
      try { 

       id = db.insertOrThrow(TABLE_NAME, null, values); 
       // Notify any watchers of the change 
       newUri = ContentUris.withAppendedId(CONTENT_URI, id); 
       getContext().getContentResolver().notifyChange(newUri, null); 

      } catch (NullPointerException e) { 
        Log.v("Error","OnInsert"+e); 
      } 
     } 
     else if (uriMatcher.match(uri) != QUADUSER) { 
      throw new IllegalArgumentException("Unknown URI bru press " + uri); 
     } 

     return newUri; 
    } 

    @Override 
    public int delete(Uri uri, String selection, String[] selectionArgs) { 
     SQLiteDatabase db = news.getWritableDatabase(); 
     int count; 
     long id;   
     Log.v("Delete",selection); 
     switch (uriMatcher.match(uri)) { 

     case QUADUSER: 
      count = db.delete(TABLE_NAME, selection, selectionArgs); 
      break; 
     case QUADUSER_ID: 
      id = Long.parseLong(uri.getPathSegments().get(1)); 
      count = db.delete(TABLE_NAME, appendRowId(selection, id), 
        selectionArgs); 
      break; 
     default: 
      throw new IllegalArgumentException("Unknown URI " + uri); 
     } 
     getContext().getContentResolver().notifyChange(uri, null); 
     return count; 
    } 

    @Override 
    public int update(Uri uri, ContentValues values, String selection, 
      String[] selectionArgs) { 
     SQLiteDatabase db = news.getWritableDatabase(); 
     int count; 
     long id;   
     switch (uriMatcher.match(uri)) { 
     case QUADUSER: 
      count = db.update(TABLE_NAME, values, selection, selectionArgs); 
      break; 
     case QUADUSER_ID: 
      id = Long.parseLong(uri.getPathSegments().get(1)); 
      count = db.update(TABLE_NAME, values, appendRowId(selection, id), 
        selectionArgs); 
      break; 
     default: 
      throw new IllegalArgumentException("Unknown URI " + uri); 
     } 

     // Notify any watchers of the change 
     getContext().getContentResolver().notifyChange(uri, null); 
     return count; 
    } 

    /** Append an id test to a SQL selection expression */ 
    private String appendRowId(String selection, long id) { 
     return _ID 
       + "=" 
       + id 
       + (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' 
         : ""); 
    } 

} 

Uwaga: przypuszczać, aby określić to Klasa dostawcy w pliku manifestu, takim jak .

W innej klasy, gdzie można wstawić i pobierania danych do DB ... jest następujący

class A extends Activity{ 

    { 

addevent(cityname,cityid); // to insert 
} 

    private void addevent(String a1, String a2) { 
     try { 
      ContentValues values = new ContentValues();   
      values.put(Constants.TITLE, a1); 
      values.put(Constants.CITYID, a2); 
      getContentResolver().insert(Constants.CONTENT_URI, values); 

     } catch (Exception e) { 
      Log.v("Error",""+e); 
     } 
    } 

pobrać ze Db

Cursor c = getContentResolver().query(Constants.CONTENT_URI, 
        null, null, null,null); 
      int a = c.getCount(); 
      Log.v("Count",""+a); 

       int columnIndex = c.getColumnIndex(Constants.TITLE); 
       int columnIndex2 = c.getColumnIndex(Constants.CITYID); 
       if (c.moveToNext()) { 
        cityName = c.getString(columnIndex); 
        city_id= c.getString(columnIndex2); 
       } 

    } 

spróbować coś takiego ... To pomoże Ci