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Android Using the SQLiteOpenHelper class


Example

public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "Example.db";
    private static final int DATABASE_VERSION = 3;

    // For all Primary Keys _id should be used as column name
    public static final String COLUMN_ID = "_id";

    // Definition of table and column names of Products table
    public static final String TABLE_PRODUCTS = "Products";
    public static final String COLUMN_NAME = "Name";
    public static final String COLUMN_DESCRIPTION = "Description";
    public static final String COLUMN_VALUE = "Value";

    // Definition of table and column names of Transactions table
    public static final String TABLE_TRANSACTIONS = "Transactions";
    public static final String COLUMN_PRODUCT_ID = "ProductId";
    public static final String COLUMN_AMOUNT = "Amount";

    // Create Statement for Products Table
    private static final String CREATE_TABLE_PRODUCT = "CREATE TABLE " + TABLE_PRODUCTS + "  (" +
            COLUMN_ID + " INTEGER PRIMARY KEY, " +
            COLUMN_DESCRIPTION + " TEXT, " +
            COLUMN_NAME + " TEXT, " +
            COLUMN_VALUE + " REAL" +
            ");";

    // Create Statement for Transactions Table
    private static final String CREATE_TABLE_TRANSACTION = "CREATE TABLE " + TABLE_TRANSACTIONS + "  (" +
            COLUMN_ID + " INTEGER PRIMARY KEY," +
            COLUMN_PRODUCT_ID + " INTEGER," +
            COLUMN_AMOUNT + " INTEGER," +
            " FOREIGN KEY (" + COLUMN_PRODUCT_ID + ") REFERENCES " + TABLE_PRODUCTS + "(" + COLUMN_ID + ")" +
            ");";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // onCreate should always create your most up to date database
        // This method is called when the app is newly installed
        db.execSQL(CREATE_TABLE_PRODUCT);
        db.execSQL(CREATE_TABLE_TRANSACTION);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // onUpgrade is responsible for upgrading the database when you make
        // changes to the schema. For each version the specific changes you made
        // in that version have to be applied.
        for (int version = oldVersion + 1; version <= newVersion; version++) {
            switch (version) {

                case 2:
                    db.execSQL("ALTER TABLE " + TABLE_PRODUCTS + " ADD COLUMN " + COLUMN_DESCRIPTION + " TEXT;");
                    break;

                case 3:
                    db.execSQL(CREATE_TABLE_TRANSACTION);
                    break;
            }
        }
    }
}