我正在向数据库中的一行添加一些值，我想知道如何获取自动生成的行_ID。我的代码如下：
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);
如何获取插入的行？
数据库类：
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;
}
}
}
答案 0 :(得分：-1)
您可以轻松选择表格中的所有行，然后移至最后一行。
示例：
String selectQuery = "SELECT * FROM " + TABLE;
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery(selectQuery, null);
if (c.moveToLast()) {
//c.getInt(c.getColumnIndex(KEY_ID))
}
答案 1 :(得分：-1)
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
}