Question

我现在正在学习数据库。我创建了一个SQLite数据库。我的布局中有6个EditText，当我点击＆＃34;保存到DB＆＃34;按钮将数据保存到DB。当我点击＆＃34; Show＆＃34;按钮，它在EditTexts中显示数据库详细信息。但问题是，当我尝试在同一个数据库中保存不同的数据时，它不会使用新数据和＆＃34;显示＆＃34;按钮仅显示旧数据。

public class FragmentFour extends Fragment {

    EditText name_ET, website_ET, bio_ET, altEmail_ET, phone_ET, facebook_ET;
    String name_str="", website_str="", bio_str="", altEmail_str="", phone_str="", facebook_str="";
    Button save, show, clear;
    private SQLiteHandler db;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_four, container, false);

      db = new SQLiteHandler(getActivity());

        name_ET = (EditText)rootView.findViewById(R.id.name);
        website_ET = (EditText)rootView.findViewById(R.id.webiste);
        bio_ET = (EditText)rootView.findViewById(R.id.bio);
        altEmail_ET = (EditText)rootView.findViewById(R.id.altEmail);
        phone_ET = (EditText)rootView.findViewById(R.id.phone);
        facebook_ET = (EditText)rootView.findViewById(R.id.facebook);

        save = (Button)rootView.findViewById(R.id.btn_save);
        show = (Button)rootView.findViewById(R.id.btn_show);
        clear = (Button)rootView.findViewById(R.id.btn_clr);

        save.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                name_str = name_ET.getText().toString();
                website_str = website_ET.getText().toString();
                bio_str = bio_ET.getText().toString();
                altEmail_str = altEmail_ET.getText().toString();
                phone_str = phone_ET.getText().toString();
                facebook_str = facebook_ET.getText().toString();

                db.addProfile(name_str, website_str, bio_str, altEmail_str, phone_str, facebook_str);
                name_ET.setText("");
                website_ET.setText("");
                bio_ET.setText("");
                altEmail_ET.setText("");
                phone_ET.setText("");
                facebook_ET.setText("");



            }
        });

        show.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                HashMap<String, String> pro = db.getProfDetails();
                String name = pro.get("name");
                String website = pro.get("website");
                String bio = pro.get("bio");
                String email = pro.get("email");
                String phone = pro.get("phone");
                String facebook = pro.get("facebook");

                name_ET.setText(name);
                website_ET.setText(website);
                bio_ET.setText(bio);
                altEmail_ET.setText(email);
                phone_ET.setText(phone);
                facebook_ET.setText(facebook);

            }
        });

        clear.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                name_ET.setText("");
                website_ET.setText("");
                bio_ET.setText("");
                altEmail_ET.setText("");
                phone_ET.setText("");
                facebook_ET.setText("");

            }
        });



        return rootView;
    }






}

SQLite数据库

public class SQLiteHandler extends SQLiteOpenHelper {

    private static final String TAG = SQLiteHandler.class.getSimpleName();

    // All Static variables
    // Database Version
    private static final int DATABASE_VERSION = 1;

    // Database Name
    private static final String DATABASE_NAME = "android_api";

    // Profile Settings table name
    private static final String TABLE_PROF = "prof";

    // Profile Settings information names
    private static final String KEY_ID = "id";
    private static final String KEY_NAME = "name";
    private static final String KEY_WEBSITE = "website";
    private static final String KEY_BIO = "bio";
    private static final String KEY_ALT_EMAIL = "alt_email";
    private static final String KEY_PHONE = "phone";
    private static final String KEY_FACEBOOK = "facebook";


    public SQLiteHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Creating Tables
    @Override
    public void onCreate(SQLiteDatabase db) {

        String CREATE_PROF_TABLE = "CREATE TABLE " + TABLE_PROF + "("+KEY_ID+" INTEGER PRIMARY KEY, "+KEY_NAME+" TEXT, "+KEY_WEBSITE+" TEXT, "+KEY_BIO+" TEXT, "+KEY_ALT_EMAIL+" TEXT, "+KEY_PHONE+" TEXT, "+KEY_FACEBOOK+" TEXT" + ")";

        db.execSQL(CREATE_PROF_TABLE);

        Log.d(TAG, "Database tables created");
    }

    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_PROF);

        // Create tables again
        onCreate(db);
    }


    /**
     * Storing Prof_settings details in database
     * */
    public void addProfile(String name, String website, String bio, String alt_email, String phone, String facebook){

        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();

        values.put(KEY_NAME, name);
        values.put(KEY_WEBSITE, website);
        values.put(KEY_BIO, bio);
        values.put(KEY_ALT_EMAIL, alt_email);
        values.put(KEY_PHONE, phone);
        values.put(KEY_FACEBOOK, facebook);

        // Inserting Row
        long id = db.insert(TABLE_PROF, null, values);
        db.close(); // Closing database connection

        Log.d(TAG, "New profile settings inserted into sqlite: " + id);

    }




    /**
     * Getting Profile Settings data from database
     * */
    public HashMap<String, String> getProfDetails() {
        HashMap<String, String> pro = new HashMap<String, String>();
        String selectQuery = "SELECT  * FROM " + TABLE_PROF;

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // Move to first row
        cursor.moveToFirst();
        if (cursor.getCount() > 0) {
            pro.put("name", cursor.getString(1));
            pro.put("website", cursor.getString(2));
            pro.put("bio", cursor.getString(3));
            pro.put("email", cursor.getString(4));
            pro.put("phone", cursor.getString(5));
            pro.put("facebook", cursor.getString(6));
        }
        cursor.close();
        db.close();
        // return log details
        Log.d(TAG, "Fetching profile details from Sqlite: " + pro.toString());

        return pro;
    }

    /**
     * Re crate database Delete all tables and create them again
     * */
    public void deleteUsers() {
        SQLiteDatabase db = this.getWritableDatabase();
        // Delete All Rows
        db.delete(TABLE_PROF, null, null);
        db.close();

        Log.d(TAG, "Deleted all profile info from sqlite");
    }

}

Answer 1

情景1

我认为数据正在保存到数据库，但问题是点击＆＃34;保存到数据库＆＃34;按钮，您将数据插入表中。

检索数据时，您会从光标（cursor.moveToFirst();）获取第一行并将其显示在EditText中。

如果数据已存在于表中，或者只是在插入新行之前删除现有行，而不是将值插入数据库，则应更新它。

如果您想清除表格

只需添加此行

即可

db.execSQL("delete from "+ TABLE_PROF);

之前

long id = db.insert(TABLE_PROF, null, values);

addProfile()方法

中的

如果您想更新现有行

使用这样的命令

db.update(TABLE_PROF, values, "_id=1", null);

但请检查是否有现有物品。如果项目不存在，只需插入行/

场景2

或者，如果要添加多行，则应在光标的最后一行（EditText）的cursor.moveToLast();中显示值。

更改

 cursor.moveToFirst();

到

 cursor.moveToLast();

然后您将看到更新的值。

Answer 2

单击该按钮，您总是在数据库中插入一个新行，代码中没有更新语句。

此外，当您查询数据库并获得光标时，该光标可用于迭代结果。你在那里做的基本上是指示光标moveToFirst而你只查询第一行。因此，即使您添加更新功能，您也将始终获得结果的第一行。

查看官方文档，了解如何更新行以及如何使用游标。

有关示例，请参阅this。

SQLite没有更新表

2 个答案: