Android SQLite 选择 IS NOT NULL

Question

我试图只检索数据库表中not NULL 的数据，但是IS NOT NULL 子句似乎不起作用。还显示空字段。

String sql = "SELECT _id, nome_sotto FROM Categorie
 WHERE nome_categoria = '"+i.getStringExtra("categoria")+"' 
AND nome_sotto IS NOT NULL ORDER BY nome_sotto  ASC";

---

private void list() {
SQLiteDatabase db = mHelper.getReadableDatabase();
final List<Dettaglio> dettagli = new ArrayList<Dettaglio>();

String sql = "SELECT _id, nome_sotto FROM Categorie
 WHERE nome_categoria = '"+i.getStringExtra("categoria")+"' 
AND nome_sotto IS NOT NULL ORDER BY nome_sotto  ASC";

Cursor c = db.rawQuery(sql, null);

    while (c.moveToNext()){
        Dettaglio d = new Dettaglio();

        d.id = c.getString(0);
        d.sottocat = c.getString(1);                                

        dettagli.add(d);
    }
    c.close();


db.close();

ListAdapter adapter....
}

Answer 1

Empty 与 null 不同。如果要过滤掉空值和空值，则需要添加:AND nome_sotto != ''