![]() A third class (Student class) will need to be implemented to hold the database entry data as it is passed between the activity and the handler. ![]() The database handler will be a subclass of SQLiteOpenHelper and will provide an abstract layer between the underlying SQLite database and the activity class. The application will consist of an activity and a database handler class (MyDBHandler class). We will create a database Android application that has a UI as follows: getReadableDatabase(): creates or opens a database for reading only.ĬontentValues allows key/value pairs to be declared consisting of table column identifiers and the values to be stored in each column.getWritableDatabase(): opens or creates a database for reading and writing.onOpen(): called when the database is opened.onUpgrade(): called in the event that the application code contains a more recent database version number reference.onCreate(): called when the database is created for the first time.SQLiteOpenHelper is designed to make it easier to create and update databases. rawQuery(): executes an SQL query statement and returns matching results in the form of a Cursor object.execSQL(): executes a single SQL Statement that does not return result data.query(): performs a specified database query and returns matching results via a Cursor object.delete(): deletes rows from a database table.insert(): inserts a new row into a database table.SQLiteDatabase provides the primary interface between the application code and underlying SQLite database. get() (such as getInt(), getDouble(), so on): returns the value of the specified contained at the specified column index of the row at the current cursor position.move(): moves by a specified offset from the current position in the result set.moveToNext(): moves to the next row in the result set.moveToLast(): moves to the last row in the result set.moveToFirst(): moves to the first row in the result set.getCount(): returns the number of rows contained within the result set.close(): release all resources used by cursor and close it.Android SQLite Java ClassesĬursor: a class provides access to the results of a database query. Like other RDBMSs, data is accessed in a SQLite database by using Structured Query Language (SQL). are standalone server processes, then SQLite is embedded because it is provided in the form of a library that is linked in applications. If most RDBMSs such as MySQL, Oracle, etc. jar files are left over in this directory, this will cause conflicts when building the project.SQLite is a relational database management system (RDBMS). only keep the files which contain modifications particular to your project.) For instance, if any of the Qt libraries or. pro file, but you should then take care to remove all unneeded files from the android/ directory (i.e. It’s possible to port old projects to the new system by setting ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android in the. Instead, the source of the project is maintained elsewhere, and you can add or overwrite parts of it if you need to by using the ANDROID_PACKAGE_SOURCE_DIR qmake variable. An android/ directory is no longer added to your project, and the contents of this directory is no longer automatically the source of the Android APK package. The way Qt for Android projects are structured has changed in Qt 5.2.0 compared to Qt 5.1.x.Please take care for QT 5.2 RC1 related possible changes Ui->msgTextEdit->append(QString("\nId:%1 Name:%2 and databasePath are class level QString variables. ![]() QDebug() msgTextEdit->append(QString("\nThe records in Table1:")) This shows a message if System is unable to Open created Database This shows a message Box if Database Connection Fails. QSqlDatabase myDB = QSqlDatabase::addDatabase("QSQLITE") QApplication::setOverrideCursor(QCursor(Qt::WaitCursor)) QMessageBox mb Void MainWindow::on_loadDatabasePushButton_clicked() QMessageBox::critical(this, "Error:", QString("Could not copy database from 'assets' to %1").arg(databasePath)) Ui->msgTextEdit->append("Database does not exist") īool copySuccess = QFile::copy( QString("assets:/databaseFileName"), databasePath ) Ui->msgTextEdit->append("databasePath: "+databasePath) // to display full name with path of database QFileInfo databaseFileInfo(QString("%1/%2").arg(tmpString).arg("databaseFileName")) ĭatabasePath = databaseFileInfo.absoluteFilePath() TmpString = QStandardPaths::writableLocation(QStandardPaths::HomeLocation) ![]() find if database exists at user's home directory location I have used Application Home Location folder to store the database after the *parent) : To bundle the database, I used the folder ''android/assets' in 'Other files' in the project. query it and returns me the data of records to display in edit box. I have created a sample test application.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |