SQLiteDatabase：Android studio自定义自动增量

Question

我是Android studio和SQLiteDatabases的新手。我需要以下方面的帮助：

数据库，成功创建并可以显示值。但是，我正在尝试为每位患者创建自定义唯一ID。 ID应介于000000-999999（6位唯一ID）之间。

应用程序的工作方式是：

1. User can "add patient"
2. User enters firstName and lastName
3. User than selects a department from a spinner
4. once the user has completed the above steps, he/she can click "Add Patient"
5. Then the values are displayed in a TabbedView, however the textView is horizontal rather than vertical.
6. and its displayed in a ListView

我已经能够实现上述所有步骤。我现在需要帮助为患者创建一个独特的id。非常感谢任何帮助

请在下面查看代码：

PatientDbHelper.java // Creates the tables and database

package tanav.sharma;

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;

/**
 * Created by Tanav on 11/4/2016.
 */
public class PatientDbHelper extends SQLiteOpenHelper {


    private static final String DATABASE_NAME = "PATIENTINFO.db";
    private static final int DATABASE_VERSION = 1;

    private static final String CREATE_QUERY =
            "CREATE TABLE "+PatientInfo.NewPatientInfo.TABLE_NAME+" ("+ PatientInfo.NewPatientInfo.PATIENT_FNAME+ " TEXT,"+PatientInfo.NewPatientInfo.PATIENT_LNAME+" TEXT,"+PatientInfo.NewPatientInfo.PATIENT_DEPARTMENT+" TEXT);";

    public PatientDbHelper(Context context){

        super(context,DATABASE_NAME,null,DATABASE_VERSION);
        Log.e("DATABASE OPERATIONS","Database created / opened ...");
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_QUERY);
        Log.e("DATABASE OPERATIONS","Table created...");

    }

    public void addInformations(String fname, String lname, String department, SQLiteDatabase db){

        ContentValues contentValues = new ContentValues();
        contentValues.put(PatientInfo.NewPatientInfo.PATIENT_FNAME,fname);
        contentValues.put(PatientInfo.NewPatientInfo.PATIENT_LNAME,lname);
        contentValues.put(PatientInfo.NewPatientInfo.PATIENT_DEPARTMENT,department);

        db.insert(PatientInfo.NewPatientInfo.TABLE_NAME, null,contentValues);

        Log.e("DATABASE OPERATIONS","One in row inserted...");
    }

    public Cursor getInformations(SQLiteDatabase db){
        Cursor cursor;
        String[] projections = {PatientInfo.NewPatientInfo.PATIENT_FNAME, PatientInfo.NewPatientInfo.PATIENT_LNAME, PatientInfo.NewPatientInfo.PATIENT_DEPARTMENT};
        cursor = db.query(PatientInfo.NewPatientInfo.TABLE_NAME,projections,null,null,null,null,null);
        return cursor;
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

PatientInfo.java //这是列等的名称。

package tanav.sharma;

/**
 * Created by Tanav on 11/4/2016.
 */
public class PatientInfo {

    public static abstract class NewPatientInfo{

        //public static final String PATIENT_ID = "patient_id";
        public static final String PATIENT_FNAME = "patient_fname";
        public static final String PATIENT_LNAME = "patient_lname";
        public static final String PATIENT_DEPARTMENT = "patient_department";

        public static final String TABLE_NAME = "patient_info";
    }
}

PatientInfoProvider.java

 package tanav.sharma;

    /**
     * Created by Tanav on 11/4/2016.
     */

public class PatientInfoProvider  {

        private String fname;
        private String lname;
        private String departments;

        public PatientInfoProvider(String fname, String lname, String departments){

            this.fname = fname;
            this.lname = lname;
            this.departments = departments;
        }

        public String getLname() {
            return lname;
        }

        public void setLname(String lname) {
            this.lname = lname;
        }

        public String getDepartments() {
            return departments;
        }

        public void setDepartments(String departments) {
            this.departments = departments;
        }

        public String getFname() {
            return fname;
        }

        public void setFname(String fname) {
            this.fname = fname;
        }
    }

以下文件是使用customText视图在listView中显示值。

PatientAdapter.java

package tanav.sharma;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by Tanav on 11/4/2016.
 */
public class PatientAdapter extends ArrayAdapter {

    List list = new ArrayList();


    public PatientAdapter(Context context, int resource) {
        super(context, resource);
    }

    static class LayoutHandler{
        TextView FNAME,LNAME,Department;
    }

    @Override
    public void add(Object object) {
        super.add(object);
        list.add(object);
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        LayoutHandler layoutHandler;
        if(row == null){
            LayoutInflater layoutInflater = (LayoutInflater)this.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row = layoutInflater.inflate(R.layout.display_all_patients,parent,false);

            layoutHandler = new LayoutHandler();
            layoutHandler.FNAME = (TextView)row.findViewById(R.id.patientNameFirst);
            layoutHandler.LNAME = (TextView)row.findViewById(R.id.patientNameLast);
            layoutHandler.Department = (TextView) row.findViewById(R.id.patientDepartment);

            row.setTag(layoutHandler);

        }else{
            layoutHandler = (LayoutHandler)row.getTag();

        }

        PatientInfoProvider patientInfoProvider = (PatientInfoProvider)this.getItem(position);
        layoutHandler.FNAME.setText(patientInfoProvider.getFname());
        layoutHandler.LNAME.setText(patientInfoProvider.getLname());
        layoutHandler.Department.setText(patientInfoProvider.getDepartments());

        return row;
    }
}

Answer 1

AUTOINCREMENT的目的是防止从以前删除的行重用ID。

<强> PatientInfo.java ID列必须是表的第一列：

public static final String PATIENT_ID = "_id";

<强> PatientDbHelper.java

private static final String CREATE_QUERY = "CREATE TABLE " + PatientInfo.NewPatientInfo.TABLE_NAME + " ("
+ PatientInfo.NewPatientInfo.PATIENT_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ PatientInfo.NewPatientInfo.PATIENT_FNAME+ " TEXT,"
+ PatientInfo.NewPatientInfo.PATIENT_LNAME+" TEXT,"
+ PatientInfo.NewPatientInfo.PATIENT_DEPARTMENT+" TEXT);";

在addInformations（）

中

if ( id != 0 ) contentValues.put(PatientInfo.NewPatientInfo.PATIENT_ID,id);

PatientInfoProvider.java

private int id;

和

public void setId(int id) {
        this.id= id;
    }

或/并更改构造函数

public PatientInfoProvider(int id, String fname, String lname, String departments){
this.id = id;
this.fname = fname;
this.lname = lname;
this.departments = departments; }

你必须在某个地方填写ID字段。如果您需要，我可以放置整个PatientInfoProvider.java

好的，那我的addInformation（）会是这样的吗？

public void addInformations(int id, String fname, String lname, String department, SQLiteDatabase db){

        ContentValues contentValues = new ContentValues();
        if ( id != 0 ) contentValues.put(PatientInfo.NewPatientInfo.PATIENT_ID, id);
        contentValues.put(PatientInfo.NewPatientInfo.PATIENT_FNAME,fname);
        contentValues.put(PatientInfo.NewPatientInfo.PATIENT_LNAME,lname);
        contentValues.put(PatientInfo.NewPatientInfo.PATIENT_DEPARTMENT,department);


        db.insert(PatientInfo.NewPatientInfo.TABLE_NAME, null,contentValues);

        Log.e("DATABASE OPERATIONS","One in row inserted...");
    }

它还给我以下错误：

Error:(50, 28) error: method addInformations in class PatientDbHelper cannot be applied to given types;
required: int,String,String,String,SQLiteDatabase
found: String,String,String,SQLiteDatabase
reason: actual and formal argument lists differ in length

所以我试着通过在我的代码中应用以下行来修复它。

public void addPatient(View view){

    int id; // Added this line
    String fname = PatientFirstName.getText().toString();
    String lname = PatientLastName.getText().toString();
    String dept = departments.getSelectedItem().toString();

    patientDbHelper = new PatientDbHelper(this);
    sqLiteDatabase = patientDbHelper.getWritableDatabase();
    patientDbHelper.addInformations(id,fname,lname,dept,sqLiteDatabase); //added 'id' in arguments..
    Toast.makeText(getBaseContext(),"Data Saved",Toast.LENGTH_LONG).show();
    patientDbHelper.close();

}

但是，addInformations中的'id'参数带有加下划线的红色，表示Variable可能尚未初始化。

我修复了一切：）

Answer 2

1-在java中用Random（）类生成一个随机数 2-如果存在此编号，则在数据库中搜索如果不存在则生成新编号使用此编号插入数据。

注意：字段 ID 是主要字段，但不是自动增量。