在我的Android应用程序项目中使用多个SQLite数据库

bqucvtff  于 2023-04-06  发布在  SQLite
关注(0)|答案(1)|浏览(165)

所以我目前正在为android编程一个闹钟应用程序，我还在学习，我想知道我是否应该为我创建的每个数据库创建一个DBHelper类，或者我如何处理通过id指向彼此的多个表。这对我来说是个问题，因为我用来自上述表的数据填充RecyclerView。现在问题开始出现，一旦我试图在运行时删除数据，表id都是主键自动递增的，所以如果我删除任何元素，这将导致id不代表数据库表的行号，可悲的是，如果在它们之前的一行中的一个项目被删除，自动递增不会处理id减少。
起初，我尝试通过sharedPreference在多个活动中传递警报数据，我希望如果应用程序崩溃，数据可以持久化，所以我切换到sqlite，我有我的DBHelper类，携带我使用的所有表：

package com.example.alarm;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

import java.util.Objects;

public class DBHelper extends SQLiteOpenHelper{
    
    Context context;

    public DBHelper(Context context, String db) {
        
        super(context, db, null, 1);
        this.context = context;
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create Table Alarmdatabase (id INTEGER primary key autoincrement, label TEXT, method_queue_id INTEGER, sound_path_id INTEGER, privilege_rights INTEGER, snoozable INTEGER, time_wake_up_hours INTEGER, time_wake_up_minutes INTEGER, days_schedule_id INTEGER, weeks_schedule_id INTEGER, check_awake INTEGER, alarm_level_table_id INTEGER)");
        //every int representing a bool is -1 for false                         this is the id of the table and the item in it, for the corresponding method

        db.execSQL("create Table Methoddatabase (id INTEGER primary key autoincrement, queue_id INTEGER, method_type_id INTEGER, method_id INTEGER, difficulty_id INTEGER, label TEXT, method_database_specific_id INTEGER)"); //multiple rows with same queue_id are part of the same queue
        db.execSQL("create Table Methodtype (id INTEGER primary key autoincrement, method_type TEXT)");
        db.execSQL("create Table Method (id INTEGER primary key autoincrement, method TEXT)");
        db.execSQL("create Table Difficulty (id INTEGER primary key autoincrement, difficulty TEXT)");

        db.execSQL("create Table Alarmlevel (id INTEGER primary key autoincrement, level_id INTEGER, method_databse_queue_id INTEGER)"); //multiple rows with the same level_id make up the different Alarmlevels, might add more attribs later

        db.execSQL("create Table QRBarcodedatabase (label TEXT primary key, decoded TEXT)");
        db.execSQL("create Table Mathdatabase (id INTEGER primary key autoincrement, method TEXT, difficulty TEXT)");
        db.execSQL("create Table Locationdatabase (id INTEGER primary key autoincrement, latitude_int INTEGER, zero_point_latitude INTEGER, longitude_int INTEGER, zero_point_longitude INTEGER, radius_int INTEGER, zero_point_radius INTEGER, street TEXT, radius_mode TEXT)");
        setupTablesForPreset(db);
    }

    private void setupTablesForPreset(SQLiteDatabase db) {

        ContentValues cv = new ContentValues();

        long res;
        for(String type : new String[]{"tap_off","math","qr_barcode","location","sudoku","memory","passphrase"}) {
            cv.put("method_type", type);
            res = db.insert("Methodtype", null, cv);
            if(res == -1){
                Toast.makeText(context, "Error setting up static Database \"Methodtype\"", Toast.LENGTH_SHORT).show();
            }
        }

        cv = new ContentValues();
        for(String type : new String[]{"null","add","sub","mult","div","fac","root","value_fx","extrema_fx","multiple_choice","reach_radius","leave_radius"}) {
            cv.put("method", type);
            res = db.insert("Method", null, cv);
            if(res == -1){
                Toast.makeText(context, "Error setting up static Database \"Method\"", Toast.LENGTH_SHORT).show();
            }
        }

        cv = new ContentValues();
        for(String type : new String[]{"ex_easy","easy","middle","hard","ex_hard"}) {
            cv.put("difficulty", type);
            res = db.insert("Difficulty", null, cv);
            if(res == -1){
                Toast.makeText(context, "Error setting up static Database \"Difficulty\"", Toast.LENGTH_SHORT).show();
            }
        }


    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int verOld, int verNew) {
        db.execSQL("drop Table if exists Alarmdatabase");

        db.execSQL("drop Table if exists Methoddatabase");
        db.execSQL("drop Table if exists Methodtype");
        db.execSQL("drop Table if exists Method");
        db.execSQL("drop Table if exists Difficulty");

        db.execSQL("drop Table if exists Alarmlevel");

        db.execSQL("drop Table if exists QRBarcodedatabase");
        db.execSQL("drop Table if exists Mathdatabase");
        db.execSQL("drop Table if exists Locationdatabase");
        onCreate(db);
    }

    //TODO: I don't need to handle SQLInjection, atleast for now, because sharing of settings is not supported as of now, so this would only harm the person itself, or be a nice niche feature lol
    //(this might change in the future, so i will keep this todo in until publishing, so if i add that feature at any point, i'll know, that i have to take care of that.)

    public void deleteRow(String table, int row_id){
        SQLiteDatabase db = this.getWritableDatabase();
        long res = db.delete(table, "id=?", new String[]{String.valueOf(row_id+2)});
        if(res ==0){
            Toast.makeText(context, "Failed deleting item: " + res, Toast.LENGTH_SHORT).show();
        }else {
            Toast.makeText(context, "Success deleting item: " +res, Toast.LENGTH_SHORT).show();
        }
    }

    public void deleteRow(String table, String label){
        SQLiteDatabase db = this.getWritableDatabase();
        long res = db.delete(table, "label=?", new String[]{label});

        if(res ==-1){
            Toast.makeText(context, "Failed deleting item", Toast.LENGTH_SHORT).show();
        }else {
            Toast.makeText(context, "Success deleting item", Toast.LENGTH_SHORT).show();
        }
    }

    public void addAlarm(String label, int methodQueueId, int soundPathId, boolean privilegeRights, boolean snoozable, int wakeUpTimeHours, int wakeUpTimeMinutes, int daysScheduleId, int weeksScheduleId, boolean checkAwake, int alarmLevelTableId){

        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        cv.put("label", label);
        cv.put("method_queue_id",methodQueueId);
        cv.put("sound_path_id",soundPathId);
        if(privilegeRights){
        cv.put("privilege_rights",1);}
        else{
            cv.put("privilege_rights", 0);}
        if(snoozable){
        cv.put("snoozable",1);}
        else{
            cv.put("snoozable",0);}
        cv.put("time_wake_up_hours", wakeUpTimeHours);
        cv.put("time_wake_up_minutes", wakeUpTimeMinutes);
        cv.put("days_schedule_id",daysScheduleId);
        cv.put("weeks_schedule_id",weeksScheduleId);
        if(checkAwake){
        cv.put("check_awake", 1);}else{
            cv.put("check_awake", 0);}
        cv.put("alarm_level_table_id",alarmLevelTableId);
        long res = db.insert("Alarmdatabase", null, cv);
        if(res == -1){
            Toast.makeText(context, "Inserting into Alarmdatabase failed", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(context, "Successfully added into Alarmdatabase", Toast.LENGTH_SHORT).show();
        }

    }

    public void addMethod(int queueID, int methodTypeId, int methodId, int difficultyId, String label, int methodDatabaseSpecificID){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        cv.put("queue_id",queueID);
        cv.put("method_type_id",methodTypeId);
        if(methodId != -1) cv.put("method_id",methodId);
        if(difficultyId != -1) cv.put("difficulty_id",difficultyId);
        if(!Objects.equals(label, "-1")) cv.put("label",label);
        cv.put("method_database_specific_id", methodDatabaseSpecificID);    //This is the id, that (if necessary) points to the specific data of the method database defined by method_type_id
                                                                            //In easy words: if you need to look up the decoded string from qrcode method, this points to the id in the specific database, that has this info
        long res = db.insert("Methoddatabase", null, cv);
        if(res == -1){
            Toast.makeText(context, "Inserting into Methoddatabase failed", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(context, "Successfully added into Methoddatabase", Toast.LENGTH_SHORT).show();
        }
    }


    public String getMethodById(int id){
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery("SELECT * FROM Method WHERE ?", new String[]{"id =" + id});

        if(c.getCount() == 0){

            return "non existent";
        }else{
            c.moveToNext();
            return c.getString(1);
            }
        }

    public String getMethodTypeById(int id){

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery("SELECT * FROM MethodType WHERE ?", new String[]{"id =" + id});

        if(c.getCount() > 0){

            c.moveToFirst();
            return c.getString(1);

        }else{
            return "non existent";

        }
    }

    public String getDifficulty(int id){
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery("SELECT * FROM Difficulty WHERE ?", new String[]{"id =" + id});

        if(c.getCount() == 0){

            return "non existent";
        }else{
            c.moveToNext();
            return c.getString(1);
        }
    }



    public int findIdByMethodType(String methodType){

        String[] methArr = new String[]{"tap_off","math","qr_barcode","location","sudoku","memory","passphrase"};
        for(int i = 0; i < methArr.length; i++) {
            if(methArr[i].equals(methodType)){
                return i+1;
            }
        }
        return -1;
    }

    public int findIdByMethod(String method){
        String[] meArr = new String[]{"null","Addition","Subtraction","Multiplication","Division","Faculty (x!)","Root","Value for f(x)","Determine extrema of f(x)","Multiple choice questions","reach_radius","leave_radius"};
        for(int i = 0; i < meArr.length; i++){
            if(meArr[i].equals(method)){
                return i+1;
            }
        }
        return -1;
    }

    public int findIdByDifficulty(String difficulty){
        switch (difficulty) {
            case "Extremely easy":
                return 1;
            case "Easy":
                return 2;
            case "Middle":
                return 3;
            case "Hard":
                return 4;
            case "Extremely hard":
                return 5;
            default:
                return -1;
        }
    }

    public void addMath(String method, String difficulty){

        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        cv.put("method",method);
        cv.put("difficulty",difficulty);
        long res = db.insert("Mathdatabase", null, cv);
        if(res == -1){
            Toast.makeText(context, "Inserting into Mathdatabase failed", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(context, "Successfully added into Mathdatabase", Toast.LENGTH_SHORT).show();
        }
    }

    public void addQRBar(String label, String decoded){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        cv.put("label", label);
        cv.put("decoded", decoded);
        long res = db.insert("QRBarcodedatabase", null, cv);
        if(res == -1){
            Toast.makeText(context, "Inserting into QRBarcodedatabase failed", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(context, "Successfully added into QRBarcodedatabase", Toast.LENGTH_SHORT).show();
        }
    }
    //        Locationdatabase latitude_int INTEGER, zero_point_latitude INTEGER, longitude_int INTEGER, zero_point_longitude INTEGER, radius_int INTEGER, zero_point_radius INTEGER, street TEXT)");

    public long addLocation(int latitudeInt, int zeroPointLatitude, int longitudeInt, int zeroPointLongitude, int radiusInt, int zeroPointRadius, String street, String radiusMode){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        cv.put("latitude_int",latitudeInt);
        cv.put("zero_point_latitude",zeroPointLatitude);
        cv.put("longitude_int",longitudeInt);
        cv.put("zero_point_longitude",zeroPointLongitude);
        cv.put("radius_int",radiusInt);
        cv.put("zero_point_radius",zeroPointRadius);
        cv.put("street",street);
        cv.put("radius_mode", radiusMode);
        long res = db.insert("Locationdatabase", null, cv);
        if(res == -1){
            Toast.makeText(context, "Inserting into Locationdatabase failed", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(context, "Successfully added into Locationdatabase", Toast.LENGTH_SHORT).show();
        }
        return res;
    }


    public void editMethoddatabase(int queue_id, int method_type_id, int method_id, int difficulty_id, String label, int method_database_spec_id, int row_id){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        if(queue_id != -1) cv.put("queue_id", queue_id);
        if(method_type_id != -1) cv.put("method_type_id", method_type_id);
        if(method_id != -1) cv.put("method_id", method_id);
        if(difficulty_id != -1) cv.put("difficulty_id", difficulty_id);
        if(!Objects.equals(label,"-1")) cv.put("label", label);
        if(method_database_spec_id != -1) cv.put("method_database_specific_id", method_database_spec_id);

        if (method_id == 1){
            editMathdatabase(getMethodById(method_id), getDifficulty(difficulty_id), method_database_spec_id);
        }

        long result = db.update("Methoddatabase", cv, "id=?", new String[]{String.valueOf(row_id)});
        if(result == -1){
            Toast.makeText(context, "Failed to update Methoddatabase", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(context, "Success updating Methoddatabase", Toast.LENGTH_SHORT).show();
        }
    }


    public void editMathdatabase(String method, String difficulty, int row_id){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues c = new ContentValues();
        if (!Objects.equals(method, "")) c.put("method", method);
        if (!Objects.equals(difficulty, "")) c.put("difficulty", difficulty);

        long r = db.update("Mathdatabase",c, "id=?", new String[]{String.valueOf(row_id)});
        if(r == -1){
            Toast.makeText(context, "Failed to update Mathdatabase", Toast.LENGTH_SHORT).show();
        }else{
            Toast.makeText(context, "Success updating Mathdatabase", Toast.LENGTH_SHORT).show();
        }

    }

    public void editLocation(int lat, int zerolat, int lon, int zerolon, int radius, int zeroradius, String street, String enter_leave, int row_id){
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues cv = new ContentValues();

        int currlat, currzerolat, currlon, currzerolon, currradius, currzeroradius;
        String currstreet, currenterleave;

        Cursor c = getData("Locationdatabase");
        if(c.getCount() > 0) {
            while(c.moveToNext()){
                if(c.getInt(0) == row_id){

                    currlat = c.getInt(1);
                    currzerolat = c.getInt(2);
                    currlon = c.getInt(3);
                    currzerolon = c.getInt(4);
                    currradius = c.getInt(5);
                    currzeroradius = c.getInt(6);
                    currstreet = c.getString(7);
                    currenterleave = c.getString(8);

                    if (lat != currlat) cv.put("latitude_int", lat);
                    if (zerolat != currzerolat) cv.put("zero_point_latitude", zerolat);
                    if (lon != currlon) cv.put("longitude_int", lon);
                    if (zerolon != currzerolon) cv.put("zero_point_longitude", zerolon);
                    if (radius != currradius) cv.put("radius_int", radius);
                    if (zeroradius != currzeroradius) cv.put("zero_point_radius", zeroradius);
                    if (!Objects.equals(street, currstreet)) cv.put("street", street);
                    if (!Objects.equals(enter_leave,currenterleave)) cv.put("radius_mode", enter_leave);
                }
            }


            long res = db.update("Locationdatabase", cv, "id=?", new String[]{String.valueOf(row_id)});
            if (res == -1) {
                Toast.makeText(context, "Failed to update Locationdatabase", Toast.LENGTH_SHORT).show();
            } else {
                Toast.makeText(context, "Success updating Locationdatabase", Toast.LENGTH_SHORT).show();
            }
        }else{
            Toast.makeText(context, "how did you manage to even get here wtf", Toast.LENGTH_SHORT).show();
        }

    }



    public Cursor getData(String database ){
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = null;

        if (db != null){
        c = db.rawQuery("Select * from "+database, null);
        }
        return c;
    }

    public Cursor execQuery(String sql, String[] selectionArgs){
        SQLiteDatabase db = this.getWritableDatabase();
        return db.rawQuery(sql, selectionArgs);

    }

}

为了不让你困惑：报警器有一个方法队列，当关闭报警器时，可以解决此问题，到目前为止，方法可以设置为定位（输入/离开半径），数学任务，扫描一个qr/条形码，轻敲关闭.我将实现一个数独，内存和一个键入你的typeprase方法. Alarm也应该能够由不同的级别组成，所以如果你解决了第一个队列的方法你可以设置x多个方法队列在那之后。级别还没有实现，但是当id改变时也会很复杂。
有没有人知道，我如何改变我的代码，所以它不会得到混淆删除一个方法从队列？

sqlite

1条答案

按热度按时间
tzcvj98z

tzcvj98z1#

so if i delete any element, this will cause the id to not represent the row number of the database table
这很好。ID不应该链接到表行。
你熟悉foreign keys吗？这就是你应该如何在多个表之间建立关系。

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