我是Android的新手，在使用SQlite数据库的应用程序上工作。不幸的是，当应用程序从数据库中检索数据时，应用程序始终崩溃。我找不到错误，所以任何提示或帮助都会非常感激。
以下是活动：
import android.app.ListActivity;
import android.content.DialogInterface;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.ListAdapter;
import android.widget.SimpleCursorAdapter;
import java.util.ArrayList;
import de.die_web_agenten.www.runinstant.db.TaskContract;
import de.die_web_agenten.www.runinstant.db.TaskDBHelper;
public class SecondListActivity extends ListActivity {
// declare class variables
private ArrayList<Item> m_parts = new ArrayList<Item>();
private Runnable viewParts;
private ItemAdapter m_adapter;
private ListAdapter listAdapter;
private TaskDBHelper helper;
/** Called when the activity is first created. */
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// instantiate our ItemAdapter class
m_adapter = new ItemAdapter(this, R.layout.list_item, m_parts);
setListAdapter(m_adapter);
// here we are defining our runnable thread.
viewParts = new Runnable(){
public void run(){
handler.sendEmptyMessage(0);
}
};
// here we call the thread we just defined - it is sent to the handler below.
Thread thread = new Thread(null, viewParts, "MagentoBackground");
thread.start();
}
private void updateUI() {
helper = new TaskDBHelper(SecondListActivity.this);
SQLiteDatabase sqlDB = helper.getReadableDatabase();
Cursor cursor = sqlDB.query(TaskContract.TABLE,
new String[]{TaskContract.Columns._id, TaskContract.Columns.SCAN_RESULT, TaskContract.Columns.SCAN_RESULT_FORMAT
},
null, null, null, null, null
);
listAdapter = new SimpleCursorAdapter(
this,
R.layout.task_view,
cursor,
new String[]{TaskContract.Columns.SCAN_RESULT_FORMAT, TaskContract.Columns.SCAN_RESULT, TaskContract.Columns._id},
new int[]{R.id.taskTextView},
0
);
this.setListAdapter(listAdapter);
}
public void onClick(DialogInterface dialogInterface, int i, Cursor cursor) {
cursor.moveToLast();
int keyIdOfRowToDelete = cursor.getInt(cursor.getColumnIndex(TaskContract.Columns._id));
SQLiteDatabase sqlDB = null;
sqlDB.delete(TaskContract.TABLE, TaskContract.Columns._id + "=?", new String[]{String.valueOf(keyIdOfRowToDelete)});
String sql = String.format("SELECT FROM %s WHERE %s = '%s'",
TaskContract.TABLE,
TaskContract.Columns.SCAN_RESULT, TaskContract.Columns.SCAN_RESULT_FORMAT);
//task);
//TaskContract.Columns.DESCRIPTION,
//description);
helper = new TaskDBHelper(SecondListActivity.this);
sqlDB = helper.getWritableDatabase();
sqlDB.execSQL(sql);
updateUI();
}
private Handler handler = new Handler()
{
public void handleMessage(Message msg)
{
// create some objects
// here is where you could also request data from a server
// and then create objects from that data.
helper = new TaskDBHelper(SecondListActivity.this);
SQLiteDatabase sqlDB = helper.getWritableDatabase();
String sql = String.format("SELECT FROM %s",
TaskContract.TABLE,
TaskContract.Columns.SCAN_RESULT_FORMAT,
TaskContract.Columns.SCAN_RESULT
);
sqlDB.execSQL(sql);
//updateUI();
String contents = TaskContract.Columns.SCAN_RESULT;
String format = TaskContract.Columns.SCAN_RESULT_FORMAT;
//Intent SecondIntent = getIntent();
//String contents = SecondIntent.getStringExtra("SCAN_RESULT");
//String contents = SecondIntent.getStringExtra("SCAN_RESULT", contents);
//String format = SecondIntent.getStringExtra("SCAN_RESULT_FORMAT");
//Intent intent = new Intent();
//String contents = intent.getStringExtra("SCAN_RESULT");
//String format = intent.getStringExtra("SCAN_RESULT_FORMAT");
//setResult(RESULT_OK, intent);
m_parts.add(new Item(contents, format, 0));
m_parts.add(new Item("MyItemName #2", "This is item #2", 0));
m_parts.add(new Item(contents, format, 0));
Log.d("CDebugTag", "Value: " + (contents));
Log.d("DDebugTag", "Value: " + (format));
//updateUI();
//Log.d("DDebugTag", "Value: " + (format));
/*m_parts.add(new Item("MyItemName", "This is item #3", 0));
m_parts.add(new Item("MyItemName #2", "This is item #4", 0));
m_parts.add(new Item("MyItemName", "This is item #5", 0));
m_parts.add(new Item("MyItemName #2", "This is item #6", 0));
m_parts.add(new Item("MyItemName", "This is item #7", 0));
m_parts.add(new Item("MyItemName #2", "This is item #8", 0));
m_parts.add(new Item("MyItemName", "This is item #9", 0));
m_parts.add(new Item("MyItemName #2", "This is item #10", 0));*/
m_adapter = new ItemAdapter(SecondListActivity.this, R.layout.list_item, m_parts);
// display the list.
setListAdapter(m_adapter);
//updateUI();
}
};
}
以下是Log Cat错误消息：
08-19 17:19:53.270 11362-11362/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: de.die_web_agenten.www.runinstant, PID: 11362
android.database.sqlite.SQLiteException: near "FROM": syntax error (code 1): , while compiling: SELECT FROM SCANDATA
#################################################################
Error Code : 1 (SQLITE_ERROR)
Caused By : SQL(query) error or missing database.
(near "FROM": syntax error (code 1): , while compiling: SELECT FROM SCANDATA)
#################################################################
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1093)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:670)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:59)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1812)
at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1743)
at de.die_web_agenten.www.runinstant.SecondListActivity$2.handleMessage(SecondListActivity.java:111)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5910)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)
任何提示和帮助将不胜感激，谢谢！
答案 0 :(得分：3)
您的查询未指定所选内容，例如
SELECT [column list] FROM SCANDATA
或
SELECT * FROM SCANDATA
答案 1 :(得分：1)
在sql查询的第二次调用中使用query而不是execSQL。由于execSQL执行单个sql查询，该查询不是SELECT或任何其他返回数据的sql语句。