更新现有的sqlite数据库中的列,但没有任何更改android
问题描述:
对不起,但我没有在网上找到任何东西。我在我的目录“资产”中使用现有的数据库。当我想更新一列时,函数返回该列已经改变,但实际上并没有发生。我试着用execSQL,但没有再次。更新现有的sqlite数据库中的列,但没有任何更改android
任何意见将不胜感激!
这里是我的DatabaseHelper代码:
public class DatabaseHelper extends SQLiteOpenHelper {
public static final String DBNAME = "program.db";
public static String DBLOCATION = "";
public static final String TableName="ProgramTable";
private Context mContext;
private SQLiteDatabase mDatabase;
public DatabaseHelper(Context context) {
super(context, DBNAME, null, 1);
this.mContext = context;
if(android.os.Build.VERSION.SDK_INT >= 17){
DBLOCATION = context.getApplicationInfo().dataDir + "/databases/";
}
else
{
DBLOCATION = "/data/data/" + context.getPackageName() + "/databases/";
}
}
@Override
public void onCreate(SQLiteDatabase db) {
}
private boolean checkDataBase()
{
File dbFile = new File(DBLOCATION + DBNAME);
return dbFile.exists();
}
//Copy the database from assets
public void copyDataBase() throws IOException
{
InputStream mInput = mContext.getAssets().open(DBNAME);
String outFileName = DBLOCATION + DBNAME;
OutputStream mOutput = new FileOutputStream(outFileName);
byte[] mBuffer = new byte[1024];
int mLength;
while ((mLength = mInput.read(mBuffer))>0)
{
mOutput.write(mBuffer, 0, mLength);
}
mOutput.flush();
mOutput.close();
mInput.close();
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public void openDatabase() {
String dbPath = mContext.getDatabasePath(DBNAME).getPath();
if (mDatabase != null && mDatabase.isOpen()) {
return;
}
mDatabase = SQLiteDatabase.openDatabase(dbPath, null, SQLiteDatabase.OPEN_READWRITE);
}
public void closeDatabase() {
if (mDatabase != null) {
mDatabase.close();
}
}
public long Like(int id) {
ContentValues contentValues = new ContentValues();
contentValues.put("Favourite",1);
mDatabase=this.getWritableDatabase();
openDatabase();
long k=mDatabase.update(TableName, contentValues, "ID =" +Integer.valueOf(id),null);
closeDatabase();
return k;
}
public long Unlike(int id) {
ContentValues contentValues = new ContentValues();
contentValues.put("Favourite",0);
mDatabase=this.getWritableDatabase();
openDatabase();
long k =mDatabase.update(TableName, contentValues, "ID ="+Integer.valueOf(id),null);
closeDatabase();
return k;
}
}
答
解决方案
我忘记用checkDatabase。在DatabaseHelper的构造函数中必须包含:
if(!checkDataBase())
{
copyDataBase();
}
答
您需要调用getWritableDatabase();
尝试交换你的代码之前先打开您的数据库。
来自:
mDatabase=this.getWritableDatabase();
openDatabase();
到:
openDatabase();
mDatabase=this.getWritableDatabase();
不起作用。 :( – EagleJ