安卓。 SQLite 异常：没有这样的列 _id

Question

Im having some troubles trying to get the info stored in my database and showing it in a ListView.

This is the ListActivity where i want to show the rows:

public class Prueba extends ListActivity{

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.i_prueba);

        DataBaseAccess db = new DataBaseAccess(this);
        db.open();

        Cursor result = db.getAllContact();
        startManagingCursor(result);


        // the desired columns to be bound
        String[] columns = new String[] {"_id", "nombre", "telefono", "mail"};
        // the XML defined views which the data will be bound to
        int[] to = new int[] { R.id.textid, R.id.textNombre, R.id.textTelefono, R.id.textMail };

        SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this, R.layout.i_listadb, result, columns, to);


        this.setListAdapter(mAdapter);

    }

The DB class. Here is the method getAllContact where i get the error:

public class DataBaseAccess {

public static final String NOMBRE = "nombre";
public static final String TELEFONO = "telefono";
public static final String MAIL = "mail";
public static final String ID = "_id";


    public DataBaseAccess(Context context) {
        this.androidContext = context;
//DataBaseHelper is another class where the Database is created. In the "onCreate" //method of that class is where i make the CREATE TABLE and add some values to that //table.
        dbHelper = new DataBaseHelper(androidContext);  
    }



    public void open() throws SQLException {
        db = dbHelper.getWritableDatabase();
        }



[...MORE METHODS...]

    public Cursor getAllContact(){
        String[] columnas = new String[] {ID, NOMBRE, TELEFONO, MAIL};
        Cursor mCursor = dbHelper.query("t_contactos", columnas, null, null, null, null, null);
    if (mCursor != null){
        mCursor.moveToFirst();
    }
    return mCursor;
}

}

And here is the error messages from the LogCat:

E/AndroidRuntime(  636): Uncaught handler: thread main exiting due to uncaught exception

E/AndroidRuntime(  636): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.pfc.android/com.pfc.android.Prueba}: android.database.sqlite.SQLiteException: no such column: _id: , while compiling: SELECT _id, nombre, telefono, mail FROM t_contactos

E/AndroidRuntime(  636):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2401)

E/AndroidRuntime(  636):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2417)

E/AndroidRuntime(  636):    at android.app.ActivityThread.access$2100(ActivityThread.java:116)

E/AndroidRuntime(  636):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)

E/AndroidRuntime(  636):    at android.os.Handler.dispatchMessage(Handler.java:99)

E/AndroidRuntime(  636):    at android.os.Looper.loop(Looper.java:123)

E/AndroidRuntime(  636):    at android.app.ActivityThread.main(ActivityThread.java:4203)

E/AndroidRuntime(  636):    at java.lang.reflect.Method.invokeNative(Native Method)

E/AndroidRuntime(  636):    at java.lang.reflect.Method.invoke(Method.java:521)

E/AndroidRuntime(  636):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)

E/AndroidRuntime(  636):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:549)

E/AndroidRuntime(  636):    at dalvik.system.NativeStart.main(Native Method)

E/AndroidRuntime(  636): Caused by: android.database.sqlite.SQLiteException: no such column: _id: , while compiling: SELECT _id, nombre, telefono, mail FROM t_contactos

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteProgram.native_compile(Native Method)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteProgram.compile(SQLiteProgram.java:110)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:59)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:49)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:49)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1118)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1006)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:964)

E/AndroidRuntime(  636):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1041)

E/AndroidRuntime(  636):    at com.pfc.android.DataBaseAccess.getAllContact(DataBaseAccess.java:97)

E/AndroidRuntime(  636):    at com.pfc.android.Prueba.onCreate(Prueba.java:21)

E/AndroidRuntime(  636):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1123)

E/AndroidRuntime(  636):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2364)

E/AndroidRuntime(  636):    ... 11 more

So, can anybody help to get through this? Thank you in advance !

Answer 1

例如，如果您使用字段“a”、“b”和“c”创建数据库并使用此数据库，那么如果您添加新字段（例如“d”），您需要在手机上重新创建数据库（只需删除它）。

Answer 2

You probably don't have a column _id in your database table. Pull the database and open it with SqliteViewer to check if it actually exists. The database is usually under /data/data/com.yourapp.package/databases/

You can use: http://sqlitebrowser.sourceforge.net/ or http://www.navicat.com/en/products/navicat_sqlite/sqlite_overview.html (they also have a free lite version)

Answer 3

Try rowid instead of _id . It works for me.

Answer 4

Right, you should create the database table before querying on it.

Here is an example:

 private static final String DATABASE_CREATE_DRIVERS =
        "create table " + DATABASE_TABLE_DRIVERS + "(" + KEY_ROWID +" integer primary key autoincrement, "
        + KEY_DRIVERID + " text not null,"
        + KEY_FIRST_NAME + " text not null,"
        + KEY_LAST_NAME + " text not null,"
        + KEY_SPEED_LIMIT + " int not null,"
        + KEY_TIMESTAMP + " int"
        + ");";

Then query on it here:

 public Cursor fetchAllDrivers(){
     Cursor mCursor =
         mDb.query(true, DATABASE_TABLE_DRIVERS, new String[] {
                 KEY_ROWID, 
                 KEY_DRIVERID,
                 KEY_FIRST_NAME,
                 KEY_LAST_NAME,
                 KEY_SPEED_LIMIT,
                 KEY_TIMESTAMP},"", null,null, null, null, null);
     if (mCursor != null) {
         mCursor.moveToFirst();
     }
     return mCursor;
 }

It also appears that you are missing a sixth argument as to what you are querying for. See where I put "" in method parameter string.

Answer 5

This is can exists 2 possiblities:

1. This problem can occurred from broken SQLite schema.

Your question is not about SQL Statement problem. but many developer can think SQL Statement problem about your question.

This case can check no demaged data in your database file. Although you can not use select fields and sql where clause by field name.

As a result, you can not use database file in your android code.

Exactly solution, I recommend recreate SQLite DB file, step by step.

You must be backup before use SQLite modification tool. (SQLite Manager, Browser, others db manage tools)

2. This problem occurred from your persistent data.

If you use the same file name for assets or raw data when run with modified data,

you can try uninstall previous installed app for refresh.

Answer 6

i change my database name, all lower_caps. it worked for me.