Question

我有一个与Android编程相关的问题。当我正在为登录和注册创建数据库，并使用Java类DBHelper时，我创建了一个与预留相关的活动。我可以使用相同的Java类（DBHelper），还是需要为类预留创建DBHelper的单独类。我希望有人能理解我的问题，也许这是愚蠢的，但我总是和机器人一样。对不起家伙

DatabaseHelper.java

package com.example.demir.carsharing;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;


public class DbHelper extends SQLiteOpenHelper {
    public static final String TAG = DbHelper.class.getSimpleName();
    public static final String DB_NAME="carsharing.db";
    public static final int DB_VERSION =1;

    public static final String USER_TABLE = "users";
    public static final String COLUMN_ID = "_id";
    public static final String COLUMN_EMAIL = "email";
    public static final String COLUMN_PASS = "password";

    /*
    * public static final String TABLE_NAME="reservation";
    public static final String COL_1="id";
    public static final String COL_2="name";
    public static final String COL_3="address";
    public static final String COL_4="phone_number";
    public static final String COL_5="starting_point";
    public static final String COL_6="destination";

    *
    * */





    /*
 create table users(
     id integer primary key autoincrement,
     email text,
     password text);
  */
    public static final String CREATE_TABLE_USERS = "CREATE TABLE " + USER_TABLE + "("
            + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
            + COLUMN_EMAIL + " TEXT,"
            + COLUMN_PASS + " TEXT);";



    public DbHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }



    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_TABLE_USERS);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXIST"+USER_TABLE);
        onCreate(db);
    }

    public void addUser(String email, String password) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(COLUMN_EMAIL, email);
        values.put(COLUMN_PASS, password);

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

        Log.d(TAG, "user inserted" + id);
    }

    public boolean getUser(String email, String pass){
        //HashMap<String, String> user = new HashMap<String, String>();
        String selectQuery = "select * from  " + USER_TABLE + " where " +
                COLUMN_EMAIL + " = " + "'"+email+"'" + " and " + COLUMN_PASS + " = " + "'"+pass+"'";

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);
        // Move to first row
        cursor.moveToFirst();
        if (cursor.getCount() > 0) {

            return true;
        }
        cursor.close();
        db.close();

        return false;
    }
}

在一个数据库Android应用程序中创建多个表

0 个答案: