Question

我尝试将数据库中的数据显示为ListView。 ListView中的每个项目都有一个位置，我使用int位置作为DELETE查询的ID，因为它是相同的。但是，它没有做任何事情。我在按钮点击事件期间调用该方法。这是SQLite数据库类的函数：

 public Cursor deleteFromRegSintomasWhereId(long id) {
    String sql = "DELETE FROM Reg_sintomas WHERE _ID= ? ; " ;
    String[] args = new String[]{id + ""};
    Cursor result = this.db.rawQuery(sql, args);
    return result;
}

这是我的活动，其中包含ListView：

   package com.example.bugdroid.menuexe.TabFragments;

import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

import com.example.bugdroid.menuexe.Activities.DetalhesSintoma;
import com.example.bugdroid.menuexe.Activities.VerRegsSintomas;
import com.example.bugdroid.menuexe.CursorAdapter.RegistosCursorAdapter;
import com.example.bugdroid.menuexe.R;
import com.example.bugdroid.menuexe.database.DAL;
import com.example.bugdroid.menuexe.database.DBAccessMode;

public class TabSintomas extends Fragment {

    private DAL dal;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        final RelativeLayout rootView = (RelativeLayout) inflater.inflate(R.layout.fragment_tab_sintomas, container, false);

        dal = new DAL(getActivity());
        dal.connect(DBAccessMode.READ);

        // Vai usar um cursor para percorrer a base de dados, usando o metodo "selectALLFromRegSintomas()" que vem da classe "DAL".
        Cursor cursor = dal.selectALLFromRegSintomas();
        // é precisar declarar o layout do fragment com que estamos a trabalhar
        final View v = inflater.inflate(R.layout.fragment_tab_sintomas, container, false);

        // Declarar a listview onde vao aparecer os dados
        ListView lv = (ListView) v.findViewById(R.id.listv);
        // Declarar o adapter que define como aparecem os dados na listview
        RegistosCursorAdapter todoAdapter = new RegistosCursorAdapter(getActivity(), cursor, 0);
        // Ligar o adapter
        lv.setAdapter(todoAdapter);

        //  Nos fragments é preciso sempre fazer return do layout que queremos mostrar, neste caso (fragment_tab_sintomas);

        lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Intent intent = new Intent(getActivity(), DetalhesSintoma.class);
                intent.putExtra("myExtras", position+1);
                startActivity(intent);
                //Toast.makeText(getActivity(),"clique",
                //        Toast.LENGTH_SHORT).show();
            }
        });
        return v;
    }
}

这是单击项目时加载的活动：

   package com.example.bugdroid.menuexe.Activities;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import com.example.bugdroid.menuexe.R;
import com.example.bugdroid.menuexe.database.DAL;
import com.example.bugdroid.menuexe.database.DBAccessMode;
import com.example.bugdroid.menuexe.database.DBContract;

import org.w3c.dom.Text;

public class DetalhesSintoma extends AppCompatActivity {

    private DAL dal;
    private TextView DataInicio;
    private EditText HoraIncio;
    private TextView DataFim;
    private EditText HoraFim;
    private TextView Intensidade;
    private TextView Motivo;
    private TextView Medicacao;
    private Button Apagar;
    private Button Concluido;
    private int position;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_detalhes_sintoma);

        DataInicio = (TextView) findViewById(R.id.DiaInicioText);
        // HoraIncio = (EditText) findViewById(R.id.HoraInicioText);
        DataFim = (TextView) findViewById(R.id.DiaFimText);
        //  HoraFim = () findViewById(R.id.HoraFimText);
        Intensidade = (TextView) findViewById(R.id.IntensidadeText);
        Motivo = (TextView) findViewById(R.id.MotivoText);
        Medicacao = (TextView) findViewById(R.id.MedicacaoText);
        Apagar = (Button) findViewById(R.id.btnApagar);
        Concluido = (Button) findViewById(R.id.btnConcluido);

        Intent intent = getIntent();
        position = intent.getIntExtra("myExtras", 0);

        dal = new DAL(this);
        dal.connect(DBAccessMode.READ);

        Cursor res = dal.selectFromRegSintomasWhereId(position);
        res.moveToFirst();
        StringBuilder datahora = new StringBuilder();
        while (!res.isAfterLast()) {
            Intensidade.setText(res.getString(res.getColumnIndex(DBContract.Reg_sintomas.COL_Intensidade)));
            String Data = res.getString(res.getColumnIndex(DBContract.Reg_sintomas.COL_D_Inicio));
            String Hora = res.getString(res.getColumnIndex(DBContract.Reg_sintomas.COL_H_Inicio));
            res.moveToNext();
            DataInicio.setText(datahora.append(Data + " ás " + Hora));
        }

        Cursor res1 = dal.selectFromRegSintomasWhereId(position);
        res1.moveToFirst();
        StringBuilder datahoraF = new StringBuilder();
        while (!res1.isAfterLast()) {
            String Data = res1.getString(res1.getColumnIndex(DBContract.Reg_sintomas.COL_D_Fim));
            String Hora = res1.getString(res1.getColumnIndex(DBContract.Reg_sintomas.COL_H_Fim));
            res1.moveToNext();
            DataFim.setText(datahoraF.append(Data + " ás " + Hora));
        }

        Cursor res2 = dal.selectFromMotivoSintomassWhereId(position);
        res2.moveToFirst();
        StringBuilder sb = new StringBuilder();
        while (!res2.isAfterLast()) {
            sb.append(res2.getString(res2.getColumnIndex(DBContract.Motivo_sintomas.COL_Motivo)));
            res2.moveToNext();
        }
        Motivo.setText(sb.toString());

        Cursor res3 = dal.selectMedicacaoWhereId(position);
        res3.moveToFirst();
        StringBuilder sb2 = new StringBuilder();
        while (!res3.isAfterLast()) {
            sb2.append(res3.getString(res3.getColumnIndex(DBContract.Medicacao.COL_Medicacao)));
            res3.moveToNext();
        }
        Medicacao.setText(sb2.toString());


        Apagar.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                dal.deleteFromRegSintomasWhereId(position);
                Intent intent = new Intent(DetalhesSintoma.this, VerRegsSintomas.class);
                startActivity(intent);
            }
        });
    }
}

这是我从上面的代码调用函数的地方：

Apagar.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            dal.deleteFromRegSintomasWhereId(position);
            Intent intent = new Intent(DetalhesSintoma.this, VerRegsSintomas.class);
            startActivity(intent);
        }
    });

如何修复此错误？有什么建议吗？

Answer 1

DELETE是命令，而不是查询。
您必须使用execSQL()执行，而不是rawQuery()。

请注意，execSQL()不会返回任何内容。

这样可以正常工作：

public void deleteFromRegSintomasWhereId(long id)
{
    String sql = "DELETE FROM Reg_sintomas WHERE _ID = ?";
    String[] args = new String[]{id};
    this.db.execSQL(sql, args);
}

删除WHERE ID无效

1 个答案: