软件工程日报11

今天练习安卓端将数据存入嵌入型数据库sqlite，实现简单单表增删改查
通过SQLiteOpenHelper来实现

public class DBHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "myapp.db";
    private static final int DATABASE_VERSION = 1;

    // 用户表创建语句
    private static final String CREATE_USER_TABLE = "CREATE TABLE users (" +
            "id INTEGER PRIMARY KEY AUTOINCREMENT, " +
            "username TEXT NOT NULL, " +
            "password TEXT NOT NULL, " +
            "gender TEXT)";

    // 商品表创建语句
    private static final String CREATE_PRODUCT_TABLE = "CREATE TABLE products (" +
            "id INTEGER PRIMARY KEY AUTOINCREMENT, " +
            "product_name TEXT NOT NULL, " +
            "product_category TEXT, " +
            "product_price REAL)";

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

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_USER_TABLE);
        db.execSQL(CREATE_PRODUCT_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS users");
        db.execSQL("DROP TABLE IF EXISTS products");
        onCreate(db);
    }
}