android数据库操作源码

public class MyDatabaseHelper extends SQLiteOpenHelper {
    private static final int DATABASE_VERSION = 2;
    private static final String DATABASE_NAME = "mydatabase.db";

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

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if (oldVersion < 2) {
            db.execSQL("ALTER TABLE mytable ADD COLUMN new_column TEXT");
        }
    }
}

Cursor cursor = db.query("mytable", null, "column = ?", new String[]{"value"}, null, null, null);
if (cursor != null && cursor.moveToFirst()) {
    // 处理查询结果
} else {
    // 查询结果为空
}

SQLiteDatabase db = dbHelper.getWritableDatabase();
db.beginTransaction();
try {
    // 执行数据库操作
    db.setTransactionSuccessful();
} finally {
    db.endTransaction();
}