![]() move() method moves by a specified offset from the current position in the result set.moveToNext() method moves to the next row in the result set.moveToLast() method moves to the last row in the result set.moveToFirst() method moves to the first row within the result set.getCount() method returns the number of rows contained within the result set.close() method releases all resources used by the cursor and closes it.Some key methods of this class are as follows: A Cursor instance can be used to step through these results, which may then be accessed from within the application code using a variety of methods. ![]() ![]() For example, a SQL SELECT operation performed on a database will potentially return multiple matching rows from the database. rawQuery() methods executes an SQL query statement and returns matching results in the form of a Cursor object.Ĭursor class provided specifically to provide access to the results of a database query.execSQL() method executes a single SQL statement that does not return result data.query() method performs a specified database query and returns matching results via a Cursor object.delete() method deletes rows from a database table.insert() method inserts a new row into a database table.SQLiteDatabase class provides the primary interface between the application code and underlying SQLite databases including the ability to create, delete and perform SQL based operations on databases. This class is of particular use when inserting or updating entries in a database table. MovieDBHelper class uses ContentValues as a convenience class that allows key/value pairs to be declared consisting of table column identifiers and the values to be stored in each column. You can check this database at any time by opening Android Device Monitor and select the package name of your app, next goto Data -> data -> and then select the folder database from the name of your app. SQLiteDatabase db = this.getReadableDatabase() Ĭursor cursor = db.rawQuery(countQuery, null) String countQuery = "SELECT * FROM " + TABLE_NAME Public void Movie(int id, String title, float rating) ) Hence we can figure out the best way to convert the database from the old schema to the new one. It passes us a SQLiteDatabase object and the old and new version numbers. onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) method called when the schema version we need does not match the schema version of the database.It passes us a SQLiteDatabase object, pointing to a newly-created database, that we can populate with tables and initial data. onCreate(SQLiteDatabase db) method called when there is no database and the app needs one.constructor takes the Context (e.g., an Activity), the name of the database, an optional cursor factory, and an integer representing the version of the database schema you are using (typically starting from 1 and increment later).We will have option to alter the database schema to match the needs of the rest of the app.įor that we’ll need to create a custom subclass of SQLiteOpenHelper implementing at least the following three methods. When the application is upgraded to a newer schema – our database will still be on the old schema from the older edition of the app.So we will have to create the tables, indexes, starter data, and so on. When the application runs the first time – at this point, we do not yet have a database.SQLiteOpenHelper designed to make it easier to create and update databases and designed to get rid of two very common problems. ![]() Android has features available to handle changing database schemas, which mostly depend on using the SQLiteOpenHelper class. This structure is referred to as a schema. We can create our own tables to hold the data accordingly. All other types must be converted into one of these fields before getting saved in the database. SQLite supports the data types TEXT (similar to String in Java), INTEGER (similar to long in Java) and REAL (similar to double in Java). Once you’ve done this, you’ll be ready to read and write to your database.
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