如何從SQL數據庫檢索行數據 - Android電子

Question

我添加數據到使用此代碼數據庫，

/** 
* Storing deck 
* */ 
public void addDeck(String id, String name, String uid, String did) { 
    SQLiteDatabase db = this.getWritableDatabase(); 

    ContentValues values = new ContentValues(); 
    values.put(KEY_DECK_ID, id); // ID 
    values.put(KEY_DECK_NAME, name); // Name 
    values.put(KEY_DECK_UID, uid); // Unique Id 
    values.put(KEY_DECK_DID, did); // Deck id 

    // Inserting Row 
    db.insert(TABLE_DECK, null, values); 
    db.close(); // Closing database connection 
} 

現在我希望能夠訪問每一行，我該怎麼辦呢？

這是我當前的代碼來訪問數據庫中的

// Getting deck data from database 
public HashMap<String, String> getDeckDetails(){ 
    HashMap<String,String> deck = new HashMap<String,String>(); 
    String selectQuery = "SELECT * FROM " + TABLE_DECK; 

    SQLiteDatabase db = this.getReadableDatabase(); 
    Cursor cursor = db.rawQuery(selectQuery, null); 
    // Move to first row 
    cursor.moveToFirst(); 
    if(cursor.getCount() > 0){ 
     deck.put("id", cursor.getString(1)); 
     deck.put("name", cursor.getString(2)); 
     deck.put("uid", cursor.getString(3)); 
     deck.put("did", cursor.getString(4)); 
    } 
    cursor.close(); 
    db.close(); 
    // return user 
    return deck; 
} 

此代碼只返回第一行的行，我怎麼能得到它返回的每一行？

Answer 1

，你必須使用一個循環：

Cursor cursor = db.rawQuery(selectQuery, null); 
while(cursor.moveToNext()){ 
    deck.put("id", cursor.getString(1)); 
    deck.put("name", cursor.getString(2)); 
    deck.put("uid", cursor.getString(3)); 
    deck.put("did", cursor.getString(4)); 
} 
cursor.close(); 

也，而不是cursor.getString(3)我會使用：

int uidPos = cursor.getColumnIndex("uid"); 
if(-1 != uidPos) cursor.getString(uidPos); 

，因爲它是更安全