Android - ต้องการดึงข้อมูลจาก SQLite แสดงที่ edittext ต้องทำอยางงัยครับ ผมลองทำแล้วมัน error ครับ ช่วยหน่อยนะครับ

package pro.example.project;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v4.widget.SimpleCursorAdapter;
import android.util.Log;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

public class UseSV extends Activity {
	private static final String TABLE_data = null;
	private EditText num1;
	private EditText num2,num3;
	private TextView tv;
	private SQLiteDatabase db;
	private EditText etId, etNum, etTax,etDat;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.usesv);
        etId= (EditText) findViewById(R.id.api_id);
        num1 = (EditText) findViewById(R.id.api_num);
        num2 = (EditText) findViewById(R.id.api_tax);
        num3 = (EditText) findViewById(R.id.api_dat);
        
      //  num1.setInputType(0);
        num2.setInputType(0);
        tv = (TextView) findViewById(R.id.api_tv);
        
        registerReceiver(br, new IntentFilter("com.mycomp.intent.r1")); //เป็นการสร้าง filter ด้วภาษาจาวา แทน xml
        
		try{
		db = openOrCreateDatabase("mydb.db", Context.MODE_PRIVATE, null);
		db.execSQL("CREATE TABLE data(_id INTEGER PRIMARY KEY , num REAL, tax REAL, dat REAL);"); 
		}catch (Exception e){
		Log.i("mylog","Error Database "+e);
		}
   }
    public void doInsert(View v) {
		String num = num1.getText().toString();
		String tax = num2.getText().toString();
		String dat = num3.getText().toString();
		db.execSQL("INSERT INTO data (num , tax, dat) VALUES('" + num + "', '"	+ tax + "', '"	+ dat + "')");
		tv.setText("Insert ok.");
	}

	public void doUpdate(View v) {
	
		String id = etId.getText().toString();
		String num = num1.getText().toString();
		String tax = num2.getText().toString();
		String dat = num3.getText().toString();
		db.execSQL("UPDATE data SET num = '"+num+"', tax = '"+tax+"', dat = '"+dat+"'WHERE _id = '"+id+"'");
		tv.setText("Update ok.");
		}	
	public void doDelete(View v) {
		String id = etId.getText().toString();
		db.execSQL("DELETE FROM data WHERE _id = '" + id + "'");
		tv.setText("Delete ok.");
	}
	// Select Data
    public String[] SelectData(String strMemberID) {
    	// TODO Auto-generated method stub
    	
    	 try {
    		String arrData[] = null;	
    		
    		 SQLiteDatabase db;
    		 db = this.getReadableDatabase(); // Read Data
    			
    		 Cursor cursor = db.query(TABLE_data, new String[] { "*" }, 
    				 	"id=?",
    		            new String[] { String.valueOf(strMemberID) }, null, null, null, null);
    		 
    		 	if(cursor != null)
    		 	{
    				if (cursor.moveToFirst()) {
    					arrData = new String[cursor.getColumnCount()];
    					/***
    					 *  0 = MemberID
    					 *  1 = Name
    					 *  2 = Tel
    					 */
    					arrData[0] = cursor.getString(0);
    					arrData[1] = cursor.getString(1);
    					arrData[2] = cursor.getString(2);
    					arrData[3] = cursor.getString(3);
    				}
    		 	}
    		 	cursor.close();
    			db.close();
    			return arrData;
    			
    	 } catch (Exception e) {
    	    return null;
    	 }

    }

    public void doQuery(View v) {
		String id = etId.getText().toString();
		//String num1 = num1.getText().toString();
		Cursor cs;
		if (id.equals("")) {
			Toast.makeText(UseSV.this, "กรุณากรอก ID ด้วยค่ะ",Toast.LENGTH_LONG).show();                   
			return;  
		} else {
			cs = db.rawQuery("SELECT * FROM data WHERE _id = "+id, null);
			String[] arrData = new String[cs.getColumnCount()];
			arrData[0] = cs.getString(0);
			arrData[1] = cs.getString(1);
			arrData[2] = cs.getString(2);
			arrData[3] = cs.getString(3);
			num1.setText(arrData[1].toString());
			num2.setText(arrData[2].toString().toString());
			num3.setText(arrData[3].toString().toString());
			
		}
		//String id = cs.getString("id");
		//String num0 = cs.getDouble("num")
		//String from[] = {"num","tax","dat"};
		//int to[] = { R.id.api_num};
		//SimpleCursorAdapter sc = new SimpleCursorAdapter(this,R.layout.usesv, cs, from, to);
		//tv.setText("");
		//num1.setText([0].toString().toString());
		//num2.setText(from[1].toString().toString());
		//num3.setText(from[2].toString().toString());
		//num1.setText(to.toString());
		
	}
 



    private SQLiteDatabase getReadableDatabase() {
	// TODO Auto-generated method stub
	return null;
}
	public void doAdd(View v) {
    	Intent i = new Intent(this, AddService.class);
    	i.putExtra("num1", num1.getText().toString());
    	i.putExtra("num2", num2.getText().toString());
    	i.putExtra("num3", num3.getText().toString());
    	startService(i);
    	
    }

    public void doHide(View v) {
    	InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    	imm.hideSoftInputFromWindow(v.getWindowToken(), // the window token to be dismissed
    								0);					// dismiss flag    	
    }
    
    public void doShow(View v){
    	InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    	imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, // show flag
                InputMethodManager.HIDE_IMPLICIT_ONLY); 	// hide flag    	
    }
    
    
    private BroadcastReceiver br = new BroadcastReceiver() {
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		tv.setText("ผลลัพธ์  = "+intent.getStringExtra("result"));
    	}   	
    };

}