Android更新时间戳

Question

我有下面的代码，它是我的DatabaseHelper，我有一个允许用户插入数据的函数，但问题是目前我试图实现的是更新我的COL4，它是TIMESTAMP。我试图添加这个代码contentValues.put(COL4, " time('now') ");，但它只打印出time('now')。任何帮助都将不胜感激，谢谢！

public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME = "scan.db";
public static final String TABLE_NAME = "scan_data";
public static final String COL1 = "ID";
public static final String COL2 = "BARCODE";
public static final String COL3 = "QUANTITY";
public static final String COL4 = "TIMESTAMP";

public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, 1);
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTable = "CREATE TABLE " + TABLE_NAME + " (ID INTEGER PRIMARY KEY AUTOINCREMENT, " +
" BARCODE TEXT, QUANTITY TEXT, TIMESTAMP DATETIME DEFAULT (DATETIME(CURRENT_TIMESTAMP, 'LOCALTIME')))";
db.execSQL(createTable);
ContentValues contentValues=new ContentValues();
contentValues.put(DatabaseHelper.COL2,263924);
contentValues.put(DatabaseHelper.COL3,1);
db.insert(DatabaseHelper.TABLE_NAME,null,contentValues);

}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
public boolean addData(String code, String quant) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL2, code);
String[] params = new String[]{code};
Cursor data = db.rawQuery("SELECT * FROM " + TABLE_NAME + " WHERE " 
+ COL2 + " = ?", params);
long result;
if (data.getCount() > 0) {
data.moveToFirst();
String[] args = new String[]{data.getString(0)};
contentValues.put(COL3, (Integer.parseInt(data.getString(2)) + Integer.parseInt(quant)));
contentValues.put(COL4, " time('now') "); // THIS LINE HERE
result = db.update(TABLE_NAME, contentValues, COL1 + "=?", args);
} else {
contentValues.put(COL3, quant);
result = db.insert(TABLE_NAME, null, contentValues);
}
//if date as inserted incorrectly it will return -1
if (result == -1) {
return false;
} else {
return true;
}
}

Answer 1

您的代码在这里有一个逻辑错误

您传递的time('now')是一个值，而不是一个变量。你所需要做的就是通过键入之类的内容来获得当前时间的值

SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd_HHmmss");
String currentDateandTime = sdf.format(new Date());