Java 登录活动的Android sqlite错误
当用户登录时,应用程序似乎会崩溃然后工作。LogCat上出现一个错误,说明:Java 登录活动的Android sqlite错误,java,android,sqlite,android-sqlite,Java,Android,Sqlite,Android Sqlite,当用户登录时,应用程序似乎会崩溃然后工作。LogCat上出现一个错误,说明: Caused by: android.database.sqlite.SQLiteException: no such column: cliff (code 1): , while compiling: SELECT DISTINCT _id, name, password FROM Users WHERE name=cliff 为什么它会抛出一个错误,然后又起作用?有人能看到我的问题吗。下面是我的代码 publ
Caused by: android.database.sqlite.SQLiteException: no such column: cliff (code 1): , while compiling: SELECT DISTINCT _id, name, password FROM Users WHERE name=cliff
为什么它会抛出一个错误,然后又起作用?有人能看到我的问题吗。下面是我的代码
public class DBAdapter {
static final String KEY_ROWID = "_id";
static final String KEY_USERNAME = "name";
static final String KEY_PASSWORD = "password";
static final String KEY_CARDNUM = "cardnum";
static final String KEY_CARDNAME = "cardname";
static final String TAG = "DBAdapter";
static final String DATABASE_NAME = "CPDB";
static final String DATABASE_TABLE = "Users";
static final String DATABASE_TABLEC = "Cards";
static final int DATABASE_VERSION = 1;
static final String DATABASE_CREATE =
"create table Users (_id integer primary key autoincrement, " + "name text not null, password text not null, cardnum integer not null, cardname text not null);";
final Context context;
DatabaseHelper DBHelper;
SQLiteDatabase db;
public DBAdapter (Context ctx){
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context){
super (context, DATABASE_NAME, null, 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 Users");
onCreate (db);
}
}
//--opens the DB--
public DBAdapter open() throws SQLException
{
db= DBHelper.getWritableDatabase();
return this;
}
//--close the DB--
public void close()
{
DBHelper.close();
}
//--retrieves chosen user--
public Cursor checkUser(String username) throws SQLException{
Cursor mCursor =
db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, KEY_USERNAME, KEY_PASSWORD}, KEY_USERNAME + "=" + username, null, null, null, null,null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
}
然后是登录java类
public class login extends Activity {
Button btn1,btn2;
@Override
public void onCreate (Bundle savedInstanceState) {
/* Called when the activity is first created*/
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
btn1 = (Button)findViewById(R.id.bttn_signup);
btn2 = (Button)findViewById(R.id.bttn_signin);
}
public void onClick(View view){
if(view.getId() == R.id.bttn_signup) {
startActivity(new Intent("com.cardpocket.cardpocket.signup"));
}
if(view.getId() == R.id.bttn_signin) {
EditText email = (EditText) findViewById(R.id.tf_email);
EditText pass = (EditText) findViewById(R.id.tf_password);
String username = email.getText().toString();
String password = pass.getText().toString();
DBAdapter db = new DBAdapter(this);
db.open();
Cursor c = db.checkUser(username);
//set someUsers as a list
ArrayList<String> theUser = new ArrayList<>();
if (c.moveToFirst()) {
do {
String aUser = c.getString(c.getColumnIndex("password"));
theUser.add(aUser);
} while (c.moveToNext());
}
if (theUser.contains(password)) {
startActivity(new Intent("com.cardpocket.cardpocket.mainactivity"));
/*
//set the value and pass to the mainactivity
Intent i = new Intent(this, mainactivity.class);
i.putExtra("username", username);
startActivity(i);}*/
} else {
//do something else
Toast.makeText(this, "No contact found", Toast.LENGTH_LONG).show();
}
}
}
公共类登录扩展活动{
按钮btn1、btn2;
@凌驾
创建时的公共void(Bundle savedInstanceState){
/*首次创建活动时调用*/
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u登录);
btn1=(按钮)findViewById(R.id.bttn_注册);
btn2=(按钮)findViewById(R.id.bttn\u sign);
}
公共void onClick(视图){
if(view.getId()==R.id.bttn\u注册){
startActivity(新意图(“com.cardpocket.cardpocket.signup”);
}
if(view.getId()==R.id.bttn\u sign){
EditText电子邮件=(EditText)findViewById(R.id.tf_电子邮件);
EditText pass=(EditText)findViewById(R.id.tf_密码);
字符串username=email.getText().toString();
字符串密码=pass.getText().toString();
DBAdapter db=新的DBAdapter(此);
db.open();
游标c=db.checkUser(用户名);
//将某些用户设置为列表
ArrayList用户=新建ArrayList();
if(c.moveToFirst()){
做{
字符串aUser=c.getString(c.getColumnIndex(“密码”);
user.add(aUser);
}而(c.moveToNext());
}
if(user.contains(密码)){
startActivity(新意图(“com.cardpocket.cardpocket.mainactivity”);
/*
//设置值并传递给mainactivity
意图i=新意图(此,mainactivity.class);
i、 putExtra(“用户名”,用户名);
星触觉(i);}*/
}否则{
//做点别的
Toast.makeText(此“未找到联系人”,Toast.LENGTH_LONG.show();
}
}
}
提前谢谢。:) 您容易受到以下影响,并且忘记引用您的价值观:
SELECT DISTINCT _id, name, password FROM Users WHERE name='cliff'
^-----^---
如果没有引号,
cliff
将被视为字段/表名,而字段/表名不存在。加上引号,'cliff'
是一个字符串文字。错误很明显:“cliff”列不存在
您必须在SQL请求中加引号
db.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, KEY_USERNAME, KEY_PASSWORD}, KEY_USERNAME + "= '" + username + "'", null, null, null, null,null);
此外,我建议您使用准备好的SQL查询,方法如下:
String selection = "KEY_USERNAME = ?";
String[] selectionArgs = { username };
String[] columns = {KEY_ROWID, KEY_USERNAME, KEY_PASSWORD};
Cursor cursor = db.query(true, DATABASE_TABLE, columns, selection, selectionArgs , null, null, null,null);
它将为您添加报价,并确保您的请求更安全
链接:您必须使用(引号)“cliff”来代替cliff。如果没有引号,sqlite会将其标识为column,并且可能会给出一个错误,没有这样的column(cliff)