[英]SQLite Cursor returning the value for one column as the value for all columns
[英]sqlite cursor returning wrong value for a column
為什么我從數據庫獲取的列url
null
?
我正在像這樣在sqlite中添加數據
void addObjects(Objects object) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(OBJECT_ID,"10" ); // OBJECT Name
values.put(OBJECT_NAME, "H"); // OBJECT Name
values.put(OBJECT_URL, "http://api.androidhive.info/images/sample.jpg"); // OBJECT URL
values.put(OBJECT_TYPE, "image"); // Contact type
System.out.println(values);
// Inserting Row
db.insert(TABLE_OBJECTS, null, values);
db.close(); // Closing database connection
}
日志值的結果www.i I/System.out﹕ TYPE=image NAME=H ID=10 URL=http://api.androidhive.info/images/sample.jpg
但是,當我得到所有結果時,我有url = null
public List<Objects> getAllObjects() {
List<Objects> Objectslist = new ArrayList<Objects>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_OBJECTS;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Objects object = new Objects();
Log.d("OBJECT_URL", OBJECT_URL);
object.setId(cursor.getInt(cursor.getColumnIndex(OBJECT_ID)));
object.setName(cursor.getString(cursor.getColumnIndex(OBJECT_NAME)));
object.setUrl(cursor.getString(cursor.getColumnIndex(OBJECT_URL)));
// Adding contact to list
Objectslist.add(object);
} while (cursor.moveToNext());
}
這是我得到sqlite結果的主要活動
List<Objects> Objects = db.getAllObjects();
Log.d("he","tttttt");
System.out.println(Objects);
DBadapter adapter = new DBadapter(getApplicationContext(), R.layout.grid_item_layout, Objects);
這是系統外包的結果
[Objects{id=10, name='http://api.androidhive.info/images/sample.jpg', url='null', type='null', category='null'}, Objects{id=10, name='http://api.androidhive.info/images/sample.jpg', url='null', type='null', category='null'}
這是全班級
public class DatabaseHandler extends SQLiteOpenHelper {
// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;
// Contacts table name
private static final String TABLE_OBJECTS = "OBJECTS";
private static final String OBJECT_ID="ID";
private static final String OBJECT_NAME="NAME";
private static final String OBJECT_TYPE ="TYPE";
private static final String OBJECT_URL ="URL";
private static final String OBJECT_CATEGORY ="CATEGORY";
private static final String OBJECT_DATE_ADDED ="DATE_ADDED";
private static final String OBJECT_USERS_ID ="USERS_ID";
private static final String OBJECT_HIDE_YN ="HIDE_YN";
public DatabaseHandler(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db){
db.execSQL("DROP TABLE IF EXISTS " + TABLE_OBJECTS);
String CREATE_OBJECTS_TABLE ="CREATE TABLE " +TABLE_OBJECTS+"("
+ OBJECT_ID +" INTEGER PRIMARY KEY AUTOINCREMENT,"
+ OBJECT_NAME +" VARCHAR(100) NULL,"
+ OBJECT_TYPE +" VARCHAR(10) NULL,"
+ OBJECT_URL +" VARCHAR(1000) NULL,"
+OBJECT_CATEGORY +" VARCHAR(50) NULL,"
+OBJECT_DATE_ADDED +" DATETIME NULL,"
+OBJECT_USERS_ID +" NUMERIC(10) NULL,"
+OBJECT_HIDE_YN +" VARCHAR(1) NULL) ";
db.execSQL(CREATE_OBJECTS_TABLE);
}
// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_OBJECTS);
// Create tables again
onCreate(db);
}
/**
* All CRUD(Create, Read, Update, Delete) Operations
*/
// Adding new contact
void addObjects(Objects object) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(OBJECT_ID,"10" ); // OBJECT Name
values.put(OBJECT_NAME, "H"); // OBJECT Name
values.put(OBJECT_URL, "http://api.androidhive.info/images/sample.jpg"); // OBJECT URL
values.put(OBJECT_TYPE, "image"); // Contact type
System.out.println(values);
// Inserting Row
long id = db.insert(TABLE_OBJECTS, null, values);
System.out.println( "id:"+id);
db.insert(TABLE_OBJECTS, null, values);
db.close(); // Closing database connection
}
// Objects object=new Objects(String );
// Getting single contact
Objects geturl(String name) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_OBJECTS, new String[] {OBJECT_URL,
OBJECT_NAME , OBJECT_CATEGORY, OBJECT_TYPE }, OBJECT_NAME + "=?",
new String[] { String.valueOf(name) }, null, null, null, null);
if (cursor != null)
cursor.moveToFirst();
Objects object = new Objects(cursor.getString(0),cursor.getString(1),
cursor.getString(2),cursor.getString(3));
return object;
}
// Getting All Contacts
public List<Objects> getAllObjects() {
List<Objects> Objectslist = new ArrayList<Objects>();
// Select All Query
String selectQuery = "SELECT * FROM " + TABLE_OBJECTS;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Objects object = new Objects();
Log.d("OBJECT_URL", OBJECT_URL);
object.setId(cursor.getInt(cursor.getColumnIndex(OBJECT_ID)));
object.setName(cursor.getString(cursor.getColumnIndex(OBJECT_NAME)));
object.setUrl(cursor.getString(cursor.getColumnIndex(OBJECT_URL)));
// Adding contact to list
Objectslist.add(object);
} while (cursor.moveToNext());
}
// return contact list
return Objectslist;
}
// Updating single contact
public int updateContact(Objects object) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(OBJECT_NAME, object.getName()); // OBJECT Name
values.put(OBJECT_URL, object.getUrl()); // OBJECT URL
values.put(OBJECT_TYPE, object.getType()); // Contact type
values.put(OBJECT_CATEGORY, object.getCategory()); // Contact category
// updating row
return db.update(TABLE_OBJECTS, values, OBJECT_ID + " = ?",
new String[] { String.valueOf(object.getId()) });
}
// Deleting single contact
public void deleteContact(Objects objects) {
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_OBJECTS, OBJECT_ID + " = ?",
new String[] { String.valueOf(objects.getId()) });
db.close();
}
// Getting contacts Count
public int getObjectsCount() {
String countQuery = "SELECT * FROM " + TABLE_OBJECTS;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(countQuery, null);
cursor.close();
// return count
return cursor.getCount();
}
}
在您的Objects geturl(String name)
方法中,更改
Cursor cursor = db.query(TABLE_OBJECTS, new String[] {OBJECT_URL,
OBJECT_NAME , OBJECT_CATEGORY, OBJECT_TYPE }, OBJECT_NAME + "=?",
new String[] { String.valueOf(name) }, null, null, null, null);
至
Cursor cursor = db.query(TABLE_OBJECTS, new String[] {OBJECT_ID,
OBJECT_NAME , OBJECT_URL, OBJECT_TYPE }, OBJECT_NAME + "=?",
new String[] { String.valueOf(name) }, null, null, null, null);
假設您的Objects類具有以下結構:
public class Objects {
private String id;
private String name;
private String url;
private String type;
// methods
}
傳遞給db.query()
方法的tableColumns
參數( new String[] {OBJECT_ID,OBJECT_NAME , OBJECT_URL, OBJECT_TYPE }
)必須遵循與Objects類相同的順序(首先是id
,2nd name
,3rd url
,第4 type
)
注意表定義中的數據類型,因為SQLite不支持MySql數據類型。 您的varchar
字段按類型相似性應該是正確的,但是text
是存儲字符串的正確方法,而不是varchar
或string
。
您還定義了datetime
,這不是一個好主意。 請改用text
或integer
(帶有時間戳)。
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