Question

我想在sqlitedatabase中只插入当前日期。根据我的理解，日期必须是整数。我想以一种我以后可以查询日期的方式插入日期。我怎样才能做到这一点？感谢

public class MyDatabase{

public static final String KEY_ROWID ="_id";
public static final String KEY_NAME ="persons_name";
public static final String KEY_ADDRESS ="persons_address";



private static final String DATABASE_NAME = "PersonsDatabase";
private static final String DATABASE_TABLE = "personsTable";
private static final int DATABASE_VERSION = 1;

private DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;

private static class DbHelper extends SQLiteOpenHelper{

    public DbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
                KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                KEY_NAME + " TEXT NOT NULL, " + 

                KEY_ADDRESS + " TEXT NOT NULL);"

                        );
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
        onCreate(db);

    }

}
public long createEntry(String name, String address) {
    // TODO Auto-generated method stub
    ContentValues cv = new ContentValues();
    cv.put(KEY_NAME , name);
    cv.put(KEY_ADDRESS, address);

    return ourDatabase.insert(DATABASE_TABLE, null, cv);

}

Answer 1

您无法在数据库中存储日期值，您只能存储字符串。您可以通过以下方式将当前日期转换为字符串：

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

...

cv.put(KEY_DATE, sdf.format(new Date(System.currentTimeMillis())));

您可以通过以下方式从db中读取日期：

String tmpString = curs.getString(curs.getColumnIndex(KEY_DATE));

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

Date dateVariable = sdf.parse(tmpString);

<强>更新

此外，您可以将timeatamp存储为长值。例如：

cv.put(KEY_DATE, System.currentTimeMillis());

要查询过去7天您需要这样做：

long sevenDaysAgo = System.currentTimeMillis() - 1000 * 60 * 60 * 24 * 7;

Cursor curs = sqLiteDB.query(DATABASE_TABLE, null, KEY_DATE + " > " + sevenDaysAgo, null, null, null, null);

Answer 2

将列创建为：

col_name TIMESTAMP DEFAULT CURRENT_TIMESTAMP

插入时忽略col_name（这将自动添加）。如果你想获得日期，你可以这样做：

private Date getDateFromCursor(Cursor cursor) {
    Timestamp dateTime = Timestamp.valueOf(cursor.getString(cursor.getColumnIndex("col_name")));
    int rawOffset = TimeZone.getDefault().getRawOffset();

    Calendar calendar = Calendar.getInstance();
    calendar.setTime(dateTime);
    calendar.add(Calendar.MILLISECOND, rawOffset);

    return calendar.getTime();
}

如何在sqlitedatabase中插入当前日期

2 个答案: