Получить строку _ID вставленной строки в базе данных SQLite - Android

Question

Я добавляю некоторые значения в строку в базе данных, и я хочу знать, как я могу получить строку _ID, которая была автоматически сгенерирована. Мой код выглядит следующим образом:

ContentValues session = new ContentValues(); 
     session.put(Database.Sessions.TIME, System.currentTimeMillis()); 
     session.put(Database.Sessions.MAP_ID, mMapId); 
     session.put(Database.Sessions.SDK_VERSION, Build.VERSION.SDK_INT); 
     session.put(Database.Sessions.MANUFACTURER, Build.MANUFACTURER); 
     session.put(Database.Sessions.MODEL, Build.MODEL); 
     getContentResolver().insert(DataProvider.SESSIONS_URI, session); 

Как получить строку, в которую она была вставлена?

класс базы данных:

import java.util.ArrayList; 
import java.util.Locale; 

import android.content.Context; 
import android.database.Cursor; 
import android.database.MatrixCursor; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.util.Log; 

public class Database extends SQLiteOpenHelper { 

    protected static final String DB_NAME = "LocalizationData.db"; 
    protected static final int DB_VERSION = 4; 

    public static final String[] TABLES = { Maps.TABLE_NAME, Scale.TABLE_NAME, 
      Readings.TABLE_NAME, Sessions.TABLE_NAME }; 
    private static final String[] SCHEMAS = { Maps.SCHEMA, Scale.SCHEMA, 
      Readings.SCHEMA, Sessions.SCHEMA }; 

    public static class Maps { 
     public static final String TABLE_NAME = "Maps"; 
     public static final String ID = "_id"; 
     public static final String NAME = "name"; 
     public static final String DATE_ADDED = "date_added"; 
     public static final String DATA = "data"; 

     private static final String ID_COLUMN = ID 
       + " INTEGER PRIMARY KEY AUTOINCREMENT"; 
     private static final String NAME_COLUMN = NAME + " TEXT NOT NULL"; 
     private static final String DATE_ADDED_COLUMN = DATE_ADDED 
       + " INTEGER NOT NULL"; 
     private static final String DATA_COLUMN = DATA + " TEXT NOT NULL"; 

     private static final String SCHEMA = generateSchema(TABLE_NAME, 
       ID_COLUMN, NAME_COLUMN, DATE_ADDED_COLUMN, DATA_COLUMN); 
    } 

    public static class Scale { 
     public static final String TABLE_NAME = "Scale"; 
     public static final String ID = "_id"; 
     public static final String MAP_SCALE = "map_scale"; 

     private static final String ID_COLUMN = ID + " INTEGER PRIMARY KEY"; 
     private static final String MAP_SCALE_COLUMN = MAP_SCALE + " FLOAT"; 
     private static final String ID_FOREIGN_COLUMN = generateForeignKeyColumn(
       ID, Maps.TABLE_NAME, Maps.ID); 

     private static final String SCHEMA = generateSchema(TABLE_NAME, 
       ID_COLUMN, MAP_SCALE_COLUMN, ID_FOREIGN_COLUMN); 
    } 

    public static class Readings { 
     public static final String TABLE_NAME = "Readings"; 
     public static final String ID = "_id"; 
     public static final String DATETIME = "datetime"; 
     public static final String MAP_X = "mapx"; 
     public static final String MAP_Y = "mapy"; 
     public static final String SIGNAL_STRENGTH = "rss"; 
     public static final String AP_NAME = "ap_name"; 
     public static final String MAC = "mac"; 
     public static final String MAP_ID = "map"; 
     public static final String SESSION_ID = "session"; 

     private static final String ID_COLUMN = ID 
       + " INTEGER PRIMARY KEY AUTOINCREMENT"; 
     private static final String DATETIME_COLUMN = DATETIME 
       + " INTEGER NOT NULL"; 
     private static final String MAP_X_COLUMN = MAP_X + " FLOAT"; 
     private static final String MAP_Y_COLUMN = MAP_Y + " FLOAT"; 
     private static final String SIGNAL_STRENGTH_COLUMN = SIGNAL_STRENGTH 
       + " INTEGER NOT NULL"; 
     private static final String AP_NAME_COLUMN = AP_NAME + " TEXT NOT NULL"; 
     private static final String MAC_COLUMN = MAC + " TEXT NOT NULL"; 
     private static final String MAP_ID_COLUMN = MAP_ID 
       + " INTEGER NOT NULL"; 
     private static final String SESSION_ID_COLUMN = SESSION_ID 
       + " INTEGER"; 
     private static final String MAP_ID_FOREIGN_COLUMN = generateForeignKeyColumn(
       MAP_ID, Maps.TABLE_NAME, Maps.ID); 

     private static final String SCHEMA = generateSchema(TABLE_NAME, 
       ID_COLUMN, DATETIME_COLUMN, MAP_X_COLUMN, MAP_Y_COLUMN, 
       SIGNAL_STRENGTH_COLUMN, AP_NAME_COLUMN, MAC_COLUMN, 
       MAP_ID_COLUMN, SESSION_ID_COLUMN, MAP_ID_FOREIGN_COLUMN); 
    } 

    public static class Sessions { 
     public static final String TABLE_NAME = "Sessions"; 
     public static final String ID = "_id"; 
     public static final String TIME = "session_datetime"; 
     public static final String MAP_ID = "map_id"; 
     public static final String SDK_VERSION = "sdk"; 
     public static final String MANUFACTURER = "maker"; 
     public static final String MODEL = "model"; 

     private static final String ID_COLUMN = ID 
       + " INTEGER PRIMARY KEY AUTOINCREMENT"; 
     private static final String TIME_COLUMN = TIME + " INTEGER NOT NULL"; 
     private static final String SDK_VERSION_COLUMN = SDK_VERSION 
       + " INTEGER NOT NULL"; 
     private static final String MANUFACTURER_COLUMN = MANUFACTURER 
       + " TEXT NOT NULL"; 
     private static final String MODEL_COLUMN = MODEL + " TEXT NOT NULL"; 
     private static final String MAP_ID_COLUMN = MAP_ID 
       + " INTEGER NOT NULL"; 
     private static final String MAP_ID_FOREIGN_COLUMN = generateForeignKeyColumn(
       MAP_ID, Maps.TABLE_NAME, Maps.ID); 

     private static final String SCHEMA = generateSchema(TABLE_NAME, 
       ID_COLUMN, TIME_COLUMN, SDK_VERSION_COLUMN, 
       MANUFACTURER_COLUMN, MODEL_COLUMN, MAP_ID_COLUMN, 
       MAP_ID_FOREIGN_COLUMN); 
    } 

    // *********************************************************************** 

    public Database(Context context) { 
     super(context, DB_NAME, null, DB_VERSION); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     Log.i("Database.onCreate", "*** Creating Tables ***"); 

     for (final String schema : SCHEMAS) { 
      Log.d("Database.onCreate", "Command = " + schema); 
      db.execSQL(schema); 
     } 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     Log.i("Database.onUpgrade", "Upgrading database from " + oldVersion 
       + " to " + newVersion); 

     Log.w("Database.onUpgrade", "Dropping and recreating tables!"); 
     for (final String tableName : TABLES) 
      db.execSQL("DROP TABLE IF EXISTS " + tableName); 

     onCreate(db); 
    } 

    protected static String generateForeignKeyColumn(String fk, 
      String refTable, String refColumn) { 
     final String format = "FOREIGN KEY(%s) REFERENCES %s(%s)"; 
     return String.format(Locale.US, format, fk, refTable, refColumn); 
    } 

    protected static String generateSchema(String tableName, 
      String... columnDefs) { 
     final StringBuilder ret = new StringBuilder(); 
     // Build beginning of CREATE statement 
     ret.append("CREATE TABLE IF NOT EXISTS "); 
     ret.append(tableName); 
     ret.append('('); 

     // Build columns of table 
     for (int i = 0; i < columnDefs.length - 1; i++) { 
      ret.append(columnDefs[i]); 
      ret.append(','); 
     } 
     if (columnDefs.length > 0) 
      ret.append(columnDefs[columnDefs.length - 1]); 

     // Build end 
     ret.append(')'); 
     ret.append(';'); 
     return ret.toString(); 
    } 

    public ArrayList<Cursor> getData(String Query){ 
     //get writable database 
     SQLiteDatabase sqlDB = this.getWritableDatabase(); 
     String[] columns = new String[] { "mesage" }; 
     //an array list of cursor to save three cursors ec_1 has results from the query 
     //other cursor stores error message if any errors are triggered 
     ArrayList<Cursor> alc = new ArrayList<Cursor>(2); 
     MatrixCursor Cursor2= new MatrixCursor(columns); 
     alc.add(null); 
     alc.add(null); 


     try{ 
      String maxQuery = Query ; 
      //execute the query results will be save in Cursor c 
      Cursor c = sqlDB.rawQuery(maxQuery, null); 


      //add value to cursor2 
      Cursor2.addRow(new Object[] { "Success" }); 

      alc.set(1,Cursor2); 
      if (null != c && c.getCount() > 0) { 


       alc.set(0,c); 
       c.moveToFirst(); 

       return alc ; 
      } 
      return alc; 
     } catch(SQLException sqlEx){ 
      Log.d("printing exception", sqlEx.getMessage()); 
      //if any exceptions are triggered save the error message to cursor an return the arraylist 
      Cursor2.addRow(new Object[] { ""+sqlEx.getMessage() }); 
      alc.set(1,Cursor2); 
      return alc; 
     } catch(Exception ex){ 

      Log.d("printing exception", ex.getMessage()); 

      //if any exceptions are triggered save the error message to cursor an return the arraylist 
      Cursor2.addRow(new Object[] { ""+ex.getMessage() }); 
      alc.set(1,Cursor2); 
      return alc; 
     } 


    } 

} 

Answer 1

Вы можете легко выбрать все строки из таблицы, а затем перейти к последней строке.

Пример:

String selectQuery = "SELECT * FROM " + TABLE; 
SQLiteDatabase db = this.getReadableDatabase(); 
Cursor c = db.rawQuery(selectQuery, null); 

if (c.moveToLast()) { 
    //c.getInt(c.getColumnIndex(KEY_ID)) 
    } 

Answer 2

Cursor c = db.query(
Database.Sessions,     // The table to query 
col_ID,      // The columns to return 
null,        // The columns for the WHERE clause 
null,        // The values for the WHERE clause 
null,        // don't group the rows 
null,        // don't filter by row groups 
null        // The sort order 
); 

if(cursor.moveToFirst()) 
{ long itemId = 
cursor.getLong(cursor.getColumnIndexOrThrow(Database.Sessions.Col_ID)); 
    } 
else { 
//your databse has some problem as curser is pointing to null 
     }