Question

我已经研究了这个并尝试更改我的数据库版本，以及重新启动应用程序，但到目前为止我没有运气。

06-04 13:58:54.803: E/AndroidRuntime(18361): FATAL EXCEPTION: main
06-04 13:58:54.803: E/AndroidRuntime(18361): android.database.sqlite.SQLiteException: no such column: _id (code 1): , while compiling: SELECT _id, user, password FROM HELLO
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1118)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:691)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1436)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1283)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1154)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1322)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at yc.android.yourchallenger.DBAdapter.getAllContacts(DBAdapter.java:98)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at yc.android.yourchallenger.LoginActivity$1.onClick(LoginActivity.java:44)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.view.View.performClick(View.java:4489)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.view.View$PerformClick.run(View.java:18803)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.os.Handler.handleCallback(Handler.java:730)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.os.Handler.dispatchMessage(Handler.java:92)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.os.Looper.loop(Looper.java:137)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at android.app.ActivityThread.main(ActivityThread.java:5493)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at java.lang.reflect.Method.invokeNative(Native Method)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at java.lang.reflect.Method.invoke(Method.java:525)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
06-04 13:58:54.803: E/AndroidRuntime(18361):    at dalvik.system.NativeStart.main(Native Method)

这是我的LoginActivity。当我按下登录按钮并将值传递到数据库时，它崩溃了。

    package yc.android.yourchallenger;

import android.app.ActionBar;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class LoginActivity extends Activity
{

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    ActionBar actionBar = getActionBar();
    actionBar.hide();

    final EditText mUserName = (EditText) findViewById(R.id.user_name);
    final EditText mPassword = (EditText) findViewById(R.id.password);

    final DBAdapter db = new DBAdapter(this);

    final Button login = (Button) findViewById(R.id.login);
    TextView signup = (TextView) findViewById(R.id.signup);

    login.setOnClickListener(new View.OnClickListener() 
    {
        public void onClick(View view) 
        {
            final String Username = mUserName.getText().toString();
            final String Password=  mPassword.getText().toString();

            db.open();

            Cursor c = db.getAllContacts();

               while(c.moveToNext())
               {
                   String c1=c.getString(2);
                   String c2=c.getString(3);

                   if(c1 == Username)
                    {
                        if(c2 == Password)
                        {
                        Toast.makeText(LoginActivity.this,                 
                        "You are succesfully logged in.",
                        Toast.LENGTH_LONG).show();

                            Intent myIntent = new Intent(view.getContext(), Menu.class);
                            startActivityForResult(myIntent, 0); 
                        }
                        else
                        {
                            Toast.makeText(LoginActivity.this, "Incorrect password",Toast.LENGTH_LONG).show();
                        }
                        Intent myIntent = new Intent(view.getContext(), LoginActivity.class);
                        startActivityForResult(myIntent, 0); 
                    }

                   else
                    Toast.makeText(LoginActivity.this, "Incorrect",Toast.LENGTH_LONG).show();
               }

            db.close();


        }
    });
    signup.setOnClickListener(new View.OnClickListener() 
    {

        @Override
        public void onClick(View arg0) 
        {
            Intent myIntent = new Intent(LoginActivity.this, SignUpActivity.class);
            startActivity(myIntent);

        }
    });
}



}

这是我的数据库

    package yc.android.yourchallenger;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
import android.widget.EditText;
import android.widget.Toast;

public class DBAdapter {
static final String KEY_ROWID = "_id";
static final String KEY_USER = "user";
static final String KEY_PASSWORD = "password";
static final String TAG = "DBAdapter";

static final String DATABASE_NAME = "HELLO";
static final String DATABASE_TABLE = "table";
static final long DATABASE_VERSION = 2;

static final String DATABASE_CREATE = 
        "create " +DATABASE_TABLE + " " + DATABASE_NAME +"(" + 
                KEY_USER + " TEXT, " + 
                KEY_PASSWORD + " TEXT);";

final Context context;

DatabaseHelper DBHelper;
SQLiteDatabase db;

public DBAdapter (Context ctx)
{
    this.context = ctx;
    DBHelper = new DatabaseHelper(ctx);
}

private static class DatabaseHelper extends SQLiteOpenHelper
{
    DatabaseHelper(Context context)
    {
        super(context, DATABASE_NAME, null, (int) DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        try {
            db.execSQL(DATABASE_CREATE);
        }
        catch(SQLException e){
            e.printStackTrace();
        }
    }

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

    //opens db database
    public DBAdapter open() throws SQLException
    {
        db = DBHelper.getWritableDatabase();
        return null;            
    }

    //closes the database
    public void close()
    {
        DBHelper.close();
    }

    //insert contacts
    public long insertContact(String userName, String password )
    {
        ContentValues initialValues = new ContentValues();
        initialValues.put(KEY_USER, userName);
        initialValues.put(KEY_PASSWORD, password);
        Toast.makeText(this.context, "contact inserted", Toast.LENGTH_SHORT).show();
        return db.insert(DATABASE_NAME, null, initialValues);
    }

    //deletes contact
    public boolean deleteContact(long rowId)
    {
        return db.delete(DATABASE_NAME, KEY_ROWID + "+" + rowId, null) > 0;
    }

    //retrieve contacts
    public Cursor getAllContacts()
    {
        return db.query(DATABASE_NAME, new String[]{KEY_ROWID, KEY_USER,
                KEY_PASSWORD}, null, null, null, null, null);
    }

    //retrieve specified contact
    public Cursor getContact(long rowId) throws SQLException
    {
        Cursor mCursor =
                db.query(true, DATABASE_NAME, new String[] {KEY_ROWID,
                KEY_USER, KEY_PASSWORD}, KEY_ROWID + "=" + rowId, null,
                null, null, null, null);
        if(mCursor!= null){
            mCursor.moveToFirst();
        }
        return mCursor;
    }

    public Boolean updatContact(long rowId, String user, String password)
    {
        ContentValues args = new ContentValues();
        args.put(KEY_USER, user);
        args.put(KEY_PASSWORD, password);
        return db.update(DATABASE_NAME, args, KEY_ROWID + "=" + rowId, null) > 0;
    }
}

Answer 1

在创建表时，您忘记添加id列。试着改变这个：

static final String DATABASE_CREATE = 
    "create " +DATABASE_TABLE + " " + DATABASE_NAME +"(" + 
            KEY_USER + " TEXT, " + 
            KEY_PASSWORD + " TEXT);";

到此：

static final String DATABASE_CREATE = 
    "create table " + DATABASE_TABLE + " ("
            + KEY_ROWID + " integer primary key autoincrement,"
            + KEY_USER + " text,"
            + KEY_USER+ " text)";

Answer 2

在SQLite中，有一个默认的id列。它有几个别名，其中没有_id。

可以使用一个与特殊情况无关的名称＆＃34; rowid＆＃34;，＆＃34; oid＆＃34;或＆＃34; _rowid _＆＃34;来访问rowid值。代替列名。

来自：http://www.sqlite.org/lang_createtable.html部分 ROWID和INTEGER PRIMARY KEY

但是，出于某种原因，android CursorAdapter要求始终在所使用的游标中包含_id列。您可以使用select rowid as _id, ...

对其进行别名

Answer 3

我认为问题在于您的DATABASE_CREATE命令。

我知道使用SQLLite创建数据库的方式就像这样

"CREATE TABLE " + DATABASE_TABLE + " ( "+ KEY_ROWID +" INTEGER PRIMARY KEY AUTOINCREMENT, "+ KEY_USER +" VARCHAR(32), "+ KEY_PASSWORD +" VARCHAR(16) );"

我认为你的命令中有2个错误。

编写命令的方式不正确。（与我相比）
您从未声明过名为＆＃34; _id＆＃34;的列。那只是失踪。

Android SQLite错误：没有这样的列_id

3 个答案: