造成的错误/ AndroidRuntime::android.database.sqlite。SQLiteException:没有此类专栏:Gurgaon:

i want display location name according city name selected from database but it gives error no such column gurgaon i save my sqlite manager data base in assets folder.... so how to run nested query in sqlite and how to store query result in a variable in android sqlite....thanks

显示我想要显示的位置名称城市名字从数据库选择但它给错误没有这样列古尔加翁我拯救我的sqlite ....资产文件夹管理器数据基地所以如何在sqlite运行嵌套查询,查询结果存储在一个变量在android sqlite ....谢谢

package cabs.h;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.R.string;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DataBaseHelper extends SQLiteOpenHelper{
   //The Android's default system path of your application database.
 private static final int DATABASE_VERSION = 1;
    private static String DB_PATH = "/data/data/cabs.h/databases/";
 private static String DB_NAME = "CabBookingDatabase.sqlite";
 private SQLiteDatabase myDataBase;
 private final Context myContext;

/**
 * Constructor
 * Takes and keeps a reference of the passed context in order to access to the application assets and resources.
 * @param context
 */
public DataBaseHelper(Context context) {

    super(context, DB_NAME, null, DATABASE_VERSION);
    this.myContext = context;
}  

/**
 * Creates a empty database on the system and rewrites it with your own database.
 * */
public void createDataBase() throws IOException{

   boolean dbExist = checkDataBase();

   if (dbExist) {
       Log.v("DB Exists", "db exists");
       // By calling this method here onUpgrade will be called on a
       // writeable database, but only if the version number has been
       // bumped
       this.getWritableDatabase();
       }
       dbExist = checkDataBase();
       if (!dbExist) {
       // By calling this method and empty database will be created into
       // the default system path of your application so we are gonna be
       // able to overwrite that database with our database.
       this.getReadableDatabase();

       try {

         copyDataBase();

      } catch (IOException e) {

          throw new Error("Error copying database");

       }
   }

}

/**
 * Check if the database already exist to avoid re-copying the file each time you open the application.
 * @return true if it exists, false if it doesn't
 */
private boolean checkDataBase(){

   SQLiteDatabase checkDB = null;

   try{
      String myPath = DB_PATH + DB_NAME;
      checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

   }catch(SQLiteException e)
   {

      //database does't exist yet.

   }

   if(checkDB != null){

      checkDB.close();

   }

   return checkDB != null ? true : false;
}

/**
 * Copies your database from your local assets-folder to the just created empty database in the
 * system folder, from where it can be accessed and handled.
 * This is done by transfering bytestream.
 * */
private void copyDataBase() throws IOException
{

   //Open your local db as the input stream
   InputStream myInput = myContext.getAssets().open(DB_NAME);

   // Path to the just created empty db
   String outFileName = DB_PATH + DB_NAME;

   //Open the empty db as the output stream
   OutputStream myOutput = new FileOutputStream(outFileName);

   //transfer bytes from the inputfile to the outputfile
   byte[] buffer = new byte[1024];
   int length;
   while ((length = myInput.read(buffer))>0){
      myOutput.write(buffer, 0, length);
   }

   //Close the streams
   myOutput.flush();
   myOutput.close();
   myInput.close();

}

public void openDataBase() throws SQLException{

   //Open the database
    String myPath = DB_PATH + DB_NAME;
   myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

}

@Override
public synchronized void close() {

       if(myDataBase != null)
          myDataBase.close();

       super.close();

}

@Override
public void onCreate(SQLiteDatabase db) { 

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w("tag", "Upgrading database from version which will destroy all old data");
    db.execSQL("DROP TABLE IF EXISTS liberQuoti");
    onCreate(db);

}

public Cursor getcity()
{
 String myPath = DB_PATH + DB_NAME;
 myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
 Cursor cur ;
 cur = myDataBase.rawQuery("select cityName from CityType", null);
 int citynameIndex = cur.getColumnIndexOrThrow("cityName");
//String valuecity = cur.getString(citynameIndex);
//Log.d("No.of tweets,,,,,,,", valuecity );

 cur.moveToFirst();
//Log.d("No.of tweets,,,,,,,", +accountnameIndex + "tgr" );
myDataBase.close();


return cur; 
}
//vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
public Cursor getloc()
{
 String myPath = DB_PATH + DB_NAME;
 myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
 Cursor cur1,cur2;
 String saa = cabbookingapplication.Selection;
 String sql="select CityType.rowid from CityType where CityType.cityName="+saa+"";
//  int sql=2;
 cur1 = myDataBase.rawQuery("select locationName from Location where cityId=("+sql+")", null);
 cur1.moveToFirst();
 myDataBase.close();
return cur1; 
}
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 public Cursor getservice()
{
 String myPath = DB_PATH + DB_NAME;
 myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
 Cursor cur3;
 cur3 = myDataBase.rawQuery("select serviceType from ServiceType", null);
 cur3.moveToFirst();
 myDataBase.close();
return cur3; 
}
public Cursor getcabtype()
{
 String myPath = DB_PATH + DB_NAME;
 myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
 Cursor cur4;
 cur4 = myDataBase.rawQuery("select carType from CarType", null);
 cur4.moveToFirst();
 myDataBase.close();
return cur4; 
}
public Cursor getcabservice()
{
 String myPath = DB_PATH + DB_NAME;
 myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
 Cursor cur5;
 cur5 = myDataBase.rawQuery("select cabFeatures from CabFeatures", null);
 cur5.moveToFirst();
 myDataBase.close();
return cur5; 
}
public Cursor getday()
{
 String myPath = DB_PATH + DB_NAME;
 myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
 Cursor cur6;
 cur6 = myDataBase.rawQuery("select dayTravell from DayTravell", null);
 cur6.moveToFirst();
 myDataBase.close();
return cur6; 
}

}

3 个解决方案

#1

1. You're closing your database when returning cursors -- thus the cursor will point to a closed database which means you can't use it (you might be able to use the first record since you moved to that before closing it). Not to mention opening/closing takes up some time. You should just open the DB once in onCreate and then close it once in onDestroy.
2. 当返回游标时，您正在关闭数据库——因此游标将指向一个关闭的数据库，这意味着您不能使用它(在关闭它之前，您可能会使用第一个记录)。更不用说开/关需要一段时间。您应该在onCreate中打开DB，然后在onDestroy中关闭它。
3. Android only supports a single SQL statement in rawQuery, so what you want cannot be achieved by nesting SQL statements
4. Android只支持rawQuery中的一个SQL语句，所以您想要的不能通过嵌套SQL语句来实现

Try something like:

尝试:

String sql = "SELECT CityType.rowid, Location.locationName FROM Location, CityType " +
    "WHERE Location.cityId = CityType.rowid " +
    "AND CityType.cityName = " + saa;

Also please post the error output from LogCat.

还请发布LogCat的错误输出。

Change your DatabaseHelper to something like the following (notice I'm not opening the database for each query - you need to make sure to call the open and close methods in the onCreate and onDestroy methods of your Activity).

将您的DatabaseHelper更改为以下内容(注意，我没有为每个查询打开数据库—您需要确保在onCreate和onDestroy方法中调用open和close方法)。

public class DataBaseHelper extends SQLiteOpenHelper {
    ...

    private SQLiteDatabase mDb;

    // change openDatabase to this:
    // call it ONCE in onCreate of your activity
    public SQLiteDatabase open() throws SQLException {
        if (mDb != null)
            return; // already opened
        mDb = this.getReadableDatabase();
        return mDb;
    }
    // call this in the onDestroy of your activity
    public void close() {
        if (mDb == null)
            return; // db is not open
        mDb.close();
        mDb = null;
    }


    // Change getLoc and your other methods to be something like this
    public Cursor getLocation() {
        if (mDb == null)
            throw new NullPointerException("Database has not been opened by activity");

        String saa = cabbookingapplication.Selection;
        String sql = "SELECT CityType.rowid, Location.locationName FROM Location, CityType " +
    "WHERE Location.cityId = CityType.rowid " +
    "AND CityType.cityName = " + saa;
        return mDb.rawQuery(sql);
    }
    ...
}

Also

也

• Make sure to call startManagingCursor on any cursors you don't close pretty much straight away to avoid memory leaks (i.e. cursors you use in adapters should be managed)
• 确保在没有立即关闭的游标上调用startManagingCursor，以避免内存泄漏(例如，应该管理您在适配器中使用的游标)
• I haven't called Cursor.moveToFirst() in my above example, so call that if you want.
• 在上面的示例中，我没有调用Cursor.moveToFirst()，所以如果需要，可以调用它。

I usually call it outside of my adapter to so I can do something like

我通常在适配器外部调用它，这样我就可以做类似的事情

if (cursor.getCount() > 0) {
    // we have at least 1 record
    while (cursor.moveToNext()) {
        // do something with current row
    }
} else {
   // no rows, show an empty message or something
}

#2

This happens on htc desire hd. For more info check here http://www.anddev.org/networking-database-problems-f29/missing-table-in-sqlite-with-specific-version-of-desire-hd-t50364.html

这发生在htc的desire hd上。有关更多信息，请访问http://www.anddev.org/network -database-problems-f29/ mis- table-in-sqlite- specific-version- desire-hd-t50364.html

#3

Try using IN instead of =:

试着用IN代替=:

String sql = "select CityType.rowid from CityType where CityType.cityName = "
    + saa;
cur1 = myDataBase.rawQuery(
    "SELECT locationName FROM Location WHERE cityId in (" + sql + ")", null);

Or simply a join:

或者只是一个连接:

String sql = "SELECT locationName FROM Location, CityType " +
    "where cityId = CityType.rowid " +
    "AND CityType.cityName = " + saa;

Apparently on some devices you may also have to close the database you open with getReadableDatabase:

显然，在某些设备上，您可能还需要关闭使用getReadableDatabase打开的数据库:

SQLiteDatabase db = getReadableDatabase();
db.close();