我正在创建一个更新数据库的应用程序，它与下面的数据库的任何列更改连接是我的代码我只想检查是否有任何列检查然后插入数据库帮助我我该怎么做？我想更新数据库表名“uss_school”，它有 8 列，都是文本字段，只是电话我测试如何在该表上添加虚拟数据？我不想删除并再次填写表我只想插入如果数据库中不存在列如何更新表？请参阅下面的屏幕截图http://imgur.com/QkKk1r8是我现在选择的查询我想要 tp 更新表的数据库“uss_school”请放置 1 行带有虚拟数据
public class DataBase extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.schoollunchapp/databases/";
private static String DB_NAME = "YummiSlice.sqlite";
private SQLiteDatabase myDataBase;
private SQLiteDatabase myData;
private final Context myContext;
public DataBase(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
CopyFiles();
}
}
private void CopyFiles()
{
try
{
InputStream is = myContext.getAssets().open(DB_NAME);
File outfile = new File(DB_PATH,DB_NAME);
outfile.getParentFile().mkdirs();
outfile.createNewFile();
if (is == null)
throw new RuntimeException("stream is null");
else
{
FileOutputStream out = new FileOutputStream(outfile);
// BufferedOutputStream out = new BufferedOutputStream( new
FileOutputStream(outfile));
byte buf[] = new byte[128];
do {
int numread = is.read(buf);
if (numread <= 0)
break;
out.write(buf, 0, numread);
} while (true);
is.close();
out.close();
}
//AssetFileDescriptor af = am.openFd("world_treasure_hunter_deluxe.apk");
}
catch (IOException e)
{
throw new RuntimeException(e);
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the
application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch(SQLiteException e){
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
@SuppressWarnings("unused")
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException{
//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
//---retrieve records---
public Cursor selectQuery(String query) throws SQLException
{
String myPath = DB_PATH + DB_NAME;
myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
Cursor mCursor =myData.rawQuery(query, null);
mCursor.moveToFirst();
myData.close();
return mCursor;
}
////////// For Insert And Update Data ////////
public void insert_update(String query) throws SQLException
{
String myPath = DB_PATH + DB_NAME;
myData = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
myData.execSQL(query);
myData.close();
}
}
DataBase db;
public class MealGroups extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mealsgroups);
db = new DataBase(getBaseContext());
try {
db.createDataBase();
} catch (IOException e1) {
e1.printStackTrace();
}
mma = new mealgroupscreenadapter(this);
new getDataTask().execute();
listmealsgroups.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> arg0, View arg1,
int position, long arg3) {
// TODO Auto-generated method stub
Intent iMenuList = new Intent(MealGroups.this, MenuGroup.class);
iMenuList.putExtra("meal_groupname",
Category_name.get(position));
iMenuList.putExtra("Meal_groupid", Category_ID.get(position));
iMenuList.putExtra("id", schedule_id);
iMenuList.putExtra("title", semestertitle);
iMenuList.putExtra("startdate", start_date);
iMenuList.putExtra("enddate", end_date);
iMenuList.putExtra("SchoolLevelId", SchoolLevelId);
iMenuList.putExtra("School_ID", School_ID);
iMenuList.putExtra("School_name", School_name);
startActivity(iMenuList);
}
});
}
public class getDataTask extends AsyncTask<Void, String, String> {
getDataTask() {
if (!prgLoading.isShown()) {
prgLoading.setVisibility(0);
}
}
@Override
protected void onPreExecute() {
super.onPreExecute();
// TODO Auto-generated method stub
}
@Override
protected String doInBackground(Void... arg0) {
// TODO Auto-generated method stub
displayData();
return _response;
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
prgLoading.setVisibility(8);
// pleaseselect.setVisibility(0);
if ((Category_ID.size() > 0)) {
listmealsgroups.setVisibility(0);
listmealsgroups.setAdapter(mma);
mma.notifyDataSetChanged();
} else {
listmealsgroups.setVisibility(View.GONE);
NoMenuAvailable.setVisibility(View.VISIBLE);
NoMenuAvailable
.setText("No Meal Group Available for this School.");
}
}
}
private void displayData() {
Cursor mCursor2 = db
.selectQuery("SELECT DISTINCT WHERE s.school_id ='"
+ School_ID + "'");
Category_ID.clear();
Category_name.clear();
if (mCursor2.moveToFirst()) {
do {
Category_ID.add(mCursor2.getString(mCursor2
.getColumnIndex("meal_group_id")));
Category_name.add(mCursor2.getString(mCursor2
.getColumnIndex("title")));
} while (mCursor2.moveToNext());
}
mCursor2.close();
}
}