java - SQLite 数据库 : Android studio custom auto incrementation

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，我试图在创建时为每个患者创建一个自定义的唯一 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

我已经能够完成上述所有步骤。我现在需要帮助为患者创建一个唯一的 ID。任何帮助将不胜感激

请看下面的代码:

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//这是列的名称等。

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";
    }
}

患者信息提供者.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;
        }
    }

以下文件用于在带有自定义 TextView 的 ListView 中显示值。

患者适配器.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 的目的是防止重复使用以前删除的行的 ID。

患者信息.javaID 列必须是表格的第一列:

public static final String PATIENT_ID = "_id";

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);

---

患者信息提供者.java

private int id;

和

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

或/和改变构造函数

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

并且您必须在某处填写 ID 字段。如果您需要，我可以将整个 PatientInfoProvider.java 放在一起

好吧，那么我的 addInformation() 看起来像这样吗？

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

所以我尝试通过将以下行应用于我的代码来修复它。

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”参数带有红色下划线，表示变量可能尚未初始化。

我已经解决了所有问题:)