Android createFromAsset迁移，但保留特定列_Android_Sqlite_Android Room

Android createFromAsset迁移，但保留特定列

android sqlite

Android createFromAsset迁移，但保留特定列,android,sqlite,android-room,Android,Sqlite,Android Room,我有一个测验应用程序，我有一个数据库，表中有所有问题，每个问题都有一个列已解决，如果答案正确，我会更新该列，因此我可以使用SQLWHERE过滤，只显示未解决的问题。现在，每隔一段时间我就要纠正问题中的拼写错误，或者可能想添加一些新的，所以如何在保留已解决的列的同时，将资产中已更正的数据库（questions.db）应用到用户设备上已保存的数据库中我想到并尝试了以下事情，但没有成功：目前，我使用自行编制的解决方案替换设备上的数据库（破坏性），但在更新之间保留已解决的信息将已解决的信息（

我有一个测验应用程序，我有一个数据库，表中有所有问题，每个问题都有一个列

已解决

，如果答案正确，我会更新该列，因此我可以使用SQL

WHERE

过滤，只显示未解决的问题。现在，每隔一段时间我就要纠正问题中的拼写错误，或者可能想添加一些新的，所以

如何在保留
已解决的列的同时，将资产中已更正的数据库（questions.db）应用到用户设备上已保存的数据库中我想到并尝试了以下事情，但没有成功：目前，我使用自行编制的解决方案替换设备上的数据库（破坏性），但在更新之间保留已解决的信息将已解决的信息（问题id已解决y/n）放在一个单独的表中，然后左连接以筛选未解决的问题，这只会使问题变得复杂有一个额外的数据库来解决问题，似乎没有简单的方法来连接两个房间的数据库因此，本质上，这可能是Room开发团队的灵感所在，我希望为createFromAsset提供一个适当的迁移策略，能够指定要保留的某些列/表。感谢您迄今为止的出色工作，我非常喜欢使用Android Jetpack和Room！另外，我很高兴能找到解决这个问题的方法：）我相信下面的方法可以满足您的需要 @Database(version = DatabaseConstants.DBVERSION, entities = {Question.class}) public abstract class QuestionDatabase extends RoomDatabase { static final String DBNAME = DatabaseConstants.DBNAME; abstract QuestionDao questionsDao(); public static QuestionDatabase getInstance(Context context) { copyFromAssets(context,false); if (getDBVersion(context,DatabaseConstants.DBNAME) < DatabaseConstants.DBVERSION) { copyFromAssets(context,true); } return Room.databaseBuilder(context,QuestionDatabase.class,DBNAME) .addCallback(callback) .allowMainThreadQueries() .addMigrations(Migration_1_2) .build(); } private static RoomDatabase.Callback callback = new Callback() { @Override public void onCreate(@NonNull SupportSQLiteDatabase db) { super.onCreate(db); } @Override public void onOpen(@NonNull SupportSQLiteDatabase db) { super.onOpen(db); } @Override public void onDestructiveMigration(@NonNull SupportSQLiteDatabase db) { super.onDestructiveMigration(db); } }; private static Migration Migration_1_2 = new Migration(1, 2) { @Override public void migrate(@NonNull SupportSQLiteDatabase database) { } }; private static boolean doesDatabaseExist(Context context) { if (new File(context.getDatabasePath(DBNAME).getPath()).exists()) return true; if (!(new File(context.getDatabasePath(DBNAME).getPath()).getParentFile()).exists()) { new File(context.getDatabasePath(DBNAME).getPath()).getParentFile().mkdirs(); } return false; } private static void copyFromAssets(Context context, boolean replaceExisting) { boolean dbExists = doesDatabaseExist(context); if (dbExists && !replaceExisting) return; //First Copy if (!replaceExisting) { copyAssetFile(context); return; } //Subsequent Copies File originalDBPath = new File(context.getDatabasePath(DBNAME).getPath()); // Open and close the original DB so as to checkpoint the WAL file SQLiteDatabase originalDB = SQLiteDatabase.openDatabase(originalDBPath.getPath(),null,SQLiteDatabase.OPEN_READWRITE); originalDB.close(); //1. Rename original database String preservedDBName = "preserved_" + DBNAME; File preservedDBPath = new File (originalDBPath.getParentFile().getPath() + preservedDBName); (new File(context.getDatabasePath(DBNAME).getPath())) .renameTo(preservedDBPath); //2. Copy the replacement database from the assets folder copyAssetFile(context); //3. Open the newly copied database SQLiteDatabase copiedDB = SQLiteDatabase.openDatabase(originalDBPath.getPath(),null,SQLiteDatabase.OPEN_READWRITE); SQLiteDatabase preservedDB = SQLiteDatabase.openDatabase(preservedDBPath.getPath(),null,SQLiteDatabase.OPEN_READONLY); //4. get the orignal data to be preserved Cursor csr = preservedDB.query( DatabaseConstants.QUESTION_TABLENAME,DatabaseConstants.EXTRACT_COLUMNS, null,null,null,null,null ); //5. Apply preserved data to the newly copied data copiedDB.beginTransaction(); ContentValues cv = new ContentValues(); while (csr.moveToNext()) { cv.clear(); for (String s: DatabaseConstants.PRESERVED_COLUMNS) { switch (csr.getType(csr.getColumnIndex(s))) { case Cursor.FIELD_TYPE_INTEGER: cv.put(s,csr.getLong(csr.getColumnIndex(s))); break; case Cursor.FIELD_TYPE_STRING: cv.put(s,csr.getString(csr.getColumnIndex(s))); break; case Cursor.FIELD_TYPE_FLOAT: cv.put(s,csr.getDouble(csr.getColumnIndex(s))); break; case Cursor.FIELD_TYPE_BLOB: cv.put(s,csr.getBlob(csr.getColumnIndex(s))); break; } } copiedDB.update( DatabaseConstants.QUESTION_TABLENAME, cv, DatabaseConstants.QUESTION_ID_COLUMN + "=?", new String[]{ String.valueOf( csr.getLong( csr.getColumnIndex(DatabaseConstants.QUESTION_ID_COLUMN ) ) ) } ); } copiedDB.setTransactionSuccessful(); copiedDB.endTransaction(); csr.close(); //6. Cleanup copiedDB.close(); preservedDB.close(); preservedDBPath.delete(); } private static void copyAssetFile(Context context) { int buffer_size = 8192; byte[] buffer = new byte[buffer_size]; int bytes_read = 0; try { InputStream fis = context.getAssets().open(DBNAME); OutputStream os = new FileOutputStream(new File(context.getDatabasePath(DBNAME).getPath())); while ((bytes_read = fis.read(buffer)) > 0) { os.write(buffer,0,bytes_read); } os.flush(); os.close(); fis.close(); } catch (IOException e) { e.printStackTrace(); throw new RuntimeException("Unable to copy from assets"); } } private static int getDBVersion(Context context, String databaseName) { SQLiteDatabase db = SQLiteDatabase.openDatabase( context.getDatabasePath(databaseName).getPath(),null,SQLiteDatabase.OPEN_READONLY); int rv = db.getVersion(); db.close(); return rv; } } 因此，可以添加要保留的其他列（根据copyFromAssets方法中的5.的任何类型）。还可以指定要提取的列，在上述情况下，ID列唯一地标识问题，以便在WHERE子句使用的已解决列之外提取问题测试已对上述各项进行了测试，以：- 起初的当DBVERSION为1时，从资产复制数据库的第一个版本请注意，本文件最初包含3个问题，根据代码的一部分（在调用活动中，检查所有已解决的值是否为0，如果是，则使用id为2更改问题的已解决状态）不复制数据库，但在子集运行中，当DBVERSION为1时，使用现有数据库。第二个问题仍未解决新的将原始资源从重命名为以原始资源为前缀后，按如下方式编辑数据库，并将其复制到资源文件中：- 在不更改DBVERSION（仍然为1）的情况下运行，并且原始数据库仍在使用中将DBVERSION更改为2后，运行将复制更改的资产文件并恢复/保留已解决状态对于后续运行，新数据的已解决状态保持不变用于测试调用活动，包括：- public class MainActivity extends AppCompatActivity { QuestionDatabase questionDatabase; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); questionDatabase = QuestionDatabase.getInstance(this); int solvedCount = 0; for (Question q: questionDatabase.questionsDao().getAll()) { if (q.isSolved()) solvedCount++; q.logQuestion(); } if (solvedCount == 0) { questionDatabase.questionsDao().setSolved(true,2); } for (Question q: questionDatabase.questionsDao().getAll()) { q.logQuestion(); } } } 对于每次运行，它将所有问题输出到日志两次。在第一个问题之后，如果没有已解决的问题，它将使用id 2解决该问题上次运行的输出为：- 附加-改进版这是一个经批准的版本，适用于多个表和列。为了满足表的需要，添加了一个类TablePreserve，该类允许表、要保留的列、要提取的列以及where子句的列。根据：- public class TablePreserve { String tableName; String[] preserveColumns; String[] extractColumns; String[] whereColumns; public TablePreserve(String table, String[] preserveColumns, String[] extractColumns, String[] whereColumns) { this.tableName = table; this.preserveColumns = preserveColumns; this.extractColumns = extractColumns; this.whereColumns = whereColumns; } public String getTableName() { return tableName; } public String[] getPreserveColumns() { return preserveColumns; } public String[] getExtractColumns() { return extractColumns; } public String[] getWhereColumns() { return whereColumns; } } 您创建一个TablePreserve对象数组，这些对象在其中循环 public final class DatabaseConstants { public static final String DBNAME = "question.db"; public static final int DBVERSION = 2; public static final String QUESTION_TABLENAME = "question"; public static final String QUESTION_ID_COLUMN = "id"; public static final String QUESTION_QUESTION_COLUMN = QUESTION_TABLENAME; public static final String QUESTION_ANSWER1_COLUMN = "answer1"; public static final String QUESTION_ANSWER2_COLUMN = "answer2"; public static final String QUESTION_ANSWER3_COLUMN = "answer3"; public static final String QUESTION_CORRECTANSWER_COLUMN = "correctAsnwer"; public static final String QUESTION_SOLVED_COLUMN = "solved"; public static final TablePreserve questionTablePreserve = new TablePreserve( QUESTION_TABLENAME, new String[]{QUESTION_SOLVED_COLUMN}, new String[]{QUESTION_ID_COLUMN,QUESTION_SOLVED_COLUMN}, new String[]{QUESTION_ID_COLUMN} ); public static final TablePreserve[] TABLE_PRESERVELIST = new TablePreserve[] { questionTablePreserve }; } 然后问题数据库变成：- @Database(version = DatabaseConstants.DBVERSION, entities = {Question.class}) public abstract class QuestionDatabase extends RoomDatabase { static final String DBNAME = DatabaseConstants.DBNAME; abstract QuestionDao questionsDao(); public static QuestionDatabase getInstance(Context context) { if (!doesDatabaseExist(context)) { copyFromAssets(context,false); } if (getDBVersion(context, DatabaseConstants.DBNAME) < DatabaseConstants.DBVERSION) { copyFromAssets(context, true); } return Room.databaseBuilder(context,QuestionDatabase.class,DBNAME) .addCallback(callback) .allowMainThreadQueries() .addMigrations(Migration_1_2) .build(); } private static RoomDatabase.Callback callback = new Callback() { @Override public void onCreate(@NonNull SupportSQLiteDatabase db) { super.onCreate(db); } @Override public void onOpen(@NonNull SupportSQLiteDatabase db) { super.onOpen(db); } @Override public void onDestructiveMigration(@NonNull SupportSQLiteDatabase db) { super.onDestructiveMigration(db); } }; private static Migration Migration_1_2 = new Migration(1, 2) { @Override public void migrate(@NonNull SupportSQLiteDatabase database) { } }; private static boolean doesDatabaseExist(Context context) { if (new File(context.getDatabasePath(DBNAME).getPath()).exists()) return true; if (!(new File(context.getDatabasePath(DBNAME).getPath()).getParentFile()).exists()) { new File(context.getDatabasePath(DBNAME).getPath()).getParentFile().mkdirs(); } return false; } private static void copyFromAssets(Context context, boolean replaceExisting) { boolean dbExists = doesDatabaseExist(context); if (dbExists && !replaceExisting) return; //First Copy if (!replaceExisting) { copyAssetFile(context); setDBVersion(context,DBNAME,DatabaseConstants.DBVERSION); return; } //Subsequent Copies File originalDBPath = new File(context.getDatabasePath(DBNAME).getPath()); // Open and close the original DB so as to checkpoint the WAL file SQLiteDatabase originalDB = SQLiteDatabase.openDatabase(originalDBPath.getPath(),null,SQLiteDatabase.OPEN_READWRITE); originalDB.close(); //1. Rename original database String preservedDBName = "preserved_" + DBNAME; File preservedDBPath = new File (originalDBPath.getParentFile().getPath() + File.separator + preservedDBName); (new File(context.getDatabasePath(DBNAME).getPath())) .renameTo(preservedDBPath); //2. Copy the replacement database from the assets folder copyAssetFile(context); //3. Open the newly copied database SQLiteDatabase copiedDB = SQLiteDatabase.openDatabase(originalDBPath.getPath(),null,SQLiteDatabase.OPEN_READWRITE); SQLiteDatabase preservedDB = SQLiteDatabase.openDatabase(preservedDBPath.getPath(),null,SQLiteDatabase.OPEN_READONLY); //4. Apply preserved data to the newly copied data copiedDB.beginTransaction(); for (TablePreserve tp: DatabaseConstants.TABLE_PRESERVELIST) { preserveTableColumns( preservedDB, copiedDB, tp.getTableName(), tp.getPreserveColumns(), tp.getExtractColumns(), tp.getWhereColumns(), true ); } copiedDB.setVersion(DatabaseConstants.DBVERSION); copiedDB.setTransactionSuccessful(); copiedDB.endTransaction(); //5. Cleanup copiedDB.close(); preservedDB.close(); preservedDBPath.delete(); } private static void copyAssetFile(Context context) { int buffer_size = 8192; byte[] buffer = new byte[buffer_size]; int bytes_read = 0; try { InputStream fis = context.getAssets().open(DBNAME); OutputStream os = new FileOutputStream(new File(context.getDatabasePath(DBNAME).getPath())); while ((bytes_read = fis.read(buffer)) > 0) { os.write(buffer,0,bytes_read); } os.flush(); os.close(); fis.close(); } catch (IOException e) { e.printStackTrace(); throw new RuntimeException("Unable to copy from assets"); } } private static int getDBVersion(Context context, String databaseName) { SQLiteDatabase db = SQLiteDatabase.openDatabase( context.getDatabasePath(databaseName).getPath(),null,SQLiteDatabase.OPEN_READONLY); int rv = db.getVersion(); db.close(); return rv; } private static void setDBVersion(Context context, String databaseName, int version) { SQLiteDatabase db = SQLiteDatabase.openDatabase( context.getDatabasePath(databaseName).getPath(),null,SQLiteDatabase.OPEN_READWRITE); db.setVersion(version); db.close(); } private static boolean preserveTableColumns( SQLiteDatabase originalDatabase, SQLiteDatabase newDatabase, String tableName, String[] columnsToPreserve, String[] columnsToExtract, String[] whereClauseColumns, boolean failWithException) { StringBuilder sb = new StringBuilder(); Cursor csr = originalDatabase.query("sqlite_master",new String[]{"name"},"name=? AND type=?",new String[]{tableName,"table"},null,null,null); if (!csr.moveToFirst()) { sb.append("\n\tTable ").append(tableName).append(" not found in database ").append(originalDatabase.getPath()); } csr = newDatabase.query("sqlite_master",new String[]{"name"},"name=? AND type=?",new String[]{tableName,"table"},null,null,null); if (!csr.moveToFirst()) { sb.append("\n\tTable ").append(tableName).append(" not found in database ").append(originalDatabase.getPath()); } if (sb.length() > 0) { if (failWithException) { throw new RuntimeException("Both databases are required to have a table named " + tableName + sb.toString()); } return false; } for (String pc: columnsToPreserve) { boolean preserveColumnInExtractedColumn = false; for (String ec: columnsToExtract) { if (pc.equals(ec)) preserveColumnInExtractedColumn = true; } if (!preserveColumnInExtractedColumn) { if (failWithException) { StringBuilder sbpc = new StringBuilder().append("Column in Columns to Preserve not found in Columns to Extract. Cannot continuue." + "\n\tColumns to Preserve are :-"); } throw new RuntimeException("Column " + pc + " is not int the Columns to Extract."); } return false; } sb = new StringBuilder(); for (String c: whereClauseColumns) { sb.append(c).append("=? "); } String[] whereargs = new String[whereClauseColumns.length]; csr = originalDatabase.query(tableName,columnsToExtract,sb.toString(),whereClauseColumns,null,null,null); ContentValues cv = new ContentValues(); while (csr.moveToNext()) { cv.clear(); for (String pc: columnsToPreserve) { switch (csr.getType(csr.getColumnIndex(pc))) { case Cursor.FIELD_TYPE_INTEGER: cv.put(pc,csr.getLong(csr.getColumnIndex(pc))); break; case Cursor.FIELD_TYPE_STRING: cv.put(pc,csr.getString(csr.getColumnIndex(pc))); break; case Cursor.FIELD_TYPE_FLOAT: cv.put(pc,csr.getDouble(csr.getColumnIndex(pc))); break; case Cursor.FIELD_TYPE_BLOB: cv.put(pc,csr.getBlob(csr.getColumnIndex(pc))); } } int waix = 0; for (String wa: whereClauseColumns) { whereargs[waix] = csr.getString(csr.getColumnIndex(wa)); } newDatabase.update(tableName,cv,sb.toString(),whereargs); } csr.close(); return true; } } @Database（version=DatabaseConstants.DBVERSION，entities={Question.class}）公共抽象类QuestionDatabase扩展了RoomDatabase{ 静态最终字符串DBNAME=DatabaseConstants.DBNAME；抽象问题dao questionsDao（）；公共静态问题数据库getInstance（上下文）{ 如果（！doesDatabaseExist（上下文））{ copyFromAssets（上下文，false）； } if（getDBVersion（context，DatabaseConstants.DBNAME）public final class DatabaseConstants { public static final String DBNAME = "question.db"; public static final int DBVERSION = 2; public static final String QUESTION_TABLENAME = "question"; public static final String QUESTION_ID_COLUMN = "id"; public static final String QUESTION_QUESTION_COLUMN = QUESTION_TABLENAME; public static final String QUESTION_ANSWER1_COLUMN = "answer1"; public static final String QUESTION_ANSWER2_COLUMN = "answer2"; public static final String QUESTION_ANSWER3_COLUMN = "answer3"; public static final String QUESTION_CORRECTANSWER_COLUMN = "correctAsnwer"; public static final String QUESTION_SOLVED_COLUMN = "solved"; public static final TablePreserve questionTablePreserve = new TablePreserve( QUESTION_TABLENAME, new String[]{QUESTION_SOLVED_COLUMN}, new String[]{QUESTION_ID_COLUMN,QUESTION_SOLVED_COLUMN}, new String[]{QUESTION_ID_COLUMN} ); public static final TablePreserve[] TABLE_PRESERVELIST = new TablePreserve[] { questionTablePreserve }; } @Database(version = DatabaseConstants.DBVERSION, entities = {Question.class}) public abstract class QuestionDatabase extends RoomDatabase { static final String DBNAME = DatabaseConstants.DBNAME; abstract QuestionDao questionsDao(); public static QuestionDatabase getInstance(Context context) { if (!doesDatabaseExist(context)) { copyFromAssets(context,false); } if (getDBVersion(context, DatabaseConstants.DBNAME) < DatabaseConstants.DBVERSION) { copyFromAssets(context, true); } return Room.databaseBuilder(context,QuestionDatabase.class,DBNAME) .addCallback(callback) .allowMainThreadQueries() .addMigrations(Migration_1_2) .build(); } private static RoomDatabase.Callback callback = new Callback() { @Override public void onCreate(@NonNull SupportSQLiteDatabase db) { super.onCreate(db); } @Override public void onOpen(@NonNull SupportSQLiteDatabase db) { super.onOpen(db); } @Override public void onDestructiveMigration(@NonNull SupportSQLiteDatabase db) { super.onDestructiveMigration(db); } }; private static Migration Migration_1_2 = new Migration(1, 2) { @Override public void migrate(@NonNull SupportSQLiteDatabase database) { } }; private static boolean doesDatabaseExist(Context context) { if (new File(context.getDatabasePath(DBNAME).getPath()).exists()) return true; if (!(new File(context.getDatabasePath(DBNAME).getPath()).getParentFile()).exists()) { new File(context.getDatabasePath(DBNAME).getPath()).getParentFile().mkdirs(); } return false; } private static void copyFromAssets(Context context, boolean replaceExisting) { boolean dbExists = doesDatabaseExist(context); if (dbExists && !replaceExisting) return; //First Copy if (!replaceExisting) { copyAssetFile(context); setDBVersion(context,DBNAME,DatabaseConstants.DBVERSION); return; } //Subsequent Copies File originalDBPath = new File(context.getDatabasePath(DBNAME).getPath()); // Open and close the original DB so as to checkpoint the WAL file SQLiteDatabase originalDB = SQLiteDatabase.openDatabase(originalDBPath.getPath(),null,SQLiteDatabase.OPEN_READWRITE); originalDB.close(); //1. Rename original database String preservedDBName = "preserved_" + DBNAME; File preservedDBPath = new File (originalDBPath.getParentFile().getPath() + File.separator + preservedDBName); (new File(context.getDatabasePath(DBNAME).getPath())) .renameTo(preservedDBPath); //2. Copy the replacement database from the assets folder copyAssetFile(context); //3. Open the newly copied database SQLiteDatabase copiedDB = SQLiteDatabase.openDatabase(originalDBPath.getPath(),null,SQLiteDatabase.OPEN_READWRITE); SQLiteDatabase preservedDB = SQLiteDatabase.openDatabase(preservedDBPath.getPath(),null,SQLiteDatabase.OPEN_READONLY); //4. Apply preserved data to the newly copied data copiedDB.beginTransaction(); for (TablePreserve tp: DatabaseConstants.TABLE_PRESERVELIST) { preserveTableColumns( preservedDB, copiedDB, tp.getTableName(), tp.getPreserveColumns(), tp.getExtractColumns(), tp.getWhereColumns(), true ); } copiedDB.setVersion(DatabaseConstants.DBVERSION); copiedDB.setTransactionSuccessful(); copiedDB.endTransaction(); //5. Cleanup copiedDB.close(); preservedDB.close(); preservedDBPath.delete(); } private static void copyAssetFile(Context context) { int buffer_size = 8192; byte[] buffer = new byte[buffer_size]; int bytes_read = 0; try { InputStream fis = context.getAssets().open(DBNAME); OutputStream os = new FileOutputStream(new File(context.getDatabasePath(DBNAME).getPath())); while ((bytes_read = fis.read(buffer)) > 0) { os.write(buffer,0,bytes_read); } os.flush(); os.close(); fis.close(); } catch (IOException e) { e.printStackTrace(); throw new RuntimeException("Unable to copy from assets"); } } private static int getDBVersion(Context context, String databaseName) { SQLiteDatabase db = SQLiteDatabase.openDatabase( context.getDatabasePath(databaseName).getPath(),null,SQLiteDatabase.OPEN_READONLY); int rv = db.getVersion(); db.close(); return rv; } private static void setDBVersion(Context context, String databaseName, int version) { SQLiteDatabase db = SQLiteDatabase.openDatabase( context.getDatabasePath(databaseName).getPath(),null,SQLiteDatabase.OPEN_READWRITE); db.setVersion(version); db.close(); } private static boolean preserveTableColumns( SQLiteDatabase originalDatabase, SQLiteDatabase newDatabase, String tableName, String[] columnsToPreserve, String[] columnsToExtract, String[] whereClauseColumns, boolean failWithException) { StringBuilder sb = new StringBuilder(); Cursor csr = originalDatabase.query("sqlite_master",new String[]{"name"},"name=? AND type=?",new String[]{tableName,"table"},null,null,null); if (!csr.moveToFirst()) { sb.append("\n\tTable ").append(tableName).append(" not found in database ").append(originalDatabase.getPath()); } csr = newDatabase.query("sqlite_master",new String[]{"name"},"name=? AND type=?",new String[]{tableName,"table"},null,null,null); if (!csr.moveToFirst()) { sb.append("\n\tTable ").append(tableName).append(" not found in database ").append(originalDatabase.getPath()); } if (sb.length() > 0) { if (failWithException) { throw new RuntimeException("Both databases are required to have a table named " + tableName + sb.toString()); } return false; } for (String pc: columnsToPreserve) { boolean preserveColumnInExtractedColumn = false; for (String ec: columnsToExtract) { if (pc.equals(ec)) preserveColumnInExtractedColumn = true; } if (!preserveColumnInExtractedColumn) { if (failWithException) { StringBuilder sbpc = new StringBuilder().append("Column in Columns to Preserve not found in Columns to Extract. Cannot continuue." + "\n\tColumns to Preserve are :-"); } throw new RuntimeException("Column " + pc + " is not int the Columns to Extract."); } return false; } sb = new StringBuilder(); for (String c: whereClauseColumns) { sb.append(c).append("=? "); } String[] whereargs = new String[whereClauseColumns.length]; csr = originalDatabase.query(tableName,columnsToExtract,sb.toString(),whereClauseColumns,null,null,null); ContentValues cv = new ContentValues(); while (csr.moveToNext()) { cv.clear(); for (String pc: columnsToPreserve) { switch (csr.getType(csr.getColumnIndex(pc))) { case Cursor.FIELD_TYPE_INTEGER: cv.put(pc,csr.getLong(csr.getColumnIndex(pc))); break; case Cursor.FIELD_TYPE_STRING: cv.put(pc,csr.getString(csr.getColumnIndex(pc))); break; case Cursor.FIELD_TYPE_FLOAT: cv.put(pc,csr.getDouble(csr.getColumnIndex(pc))); break; case Cursor.FIELD_TYPE_BLOB: cv.put(pc,csr.getBlob(csr.getColumnIndex(pc))); } } int waix = 0; for (String wa: whereClauseColumns) { whereargs[waix] = csr.getString(csr.getColumnIndex(wa)); } newDatabase.update(tableName,cv,sb.toString(),whereargs); } csr.close(); return true; } }