如何在Android应用程序中使用SQLite？

Question

How can I ensure that my tables are created and where can I find my database in android? I ran this code but it stores only one record in my tables. How can this problem be solved? I have created two classes

FIRST CLASS:

 public class dataAccess {
     private SQLiteDatabase database;
     private sqliteHelper dbHelper;

     public dataAccess(Context context) 
     {
          dbHelper = new sqliteHelper(context);
     }

     public void open() throws SQLException 
     {
       database = dbHelper.getWritableDatabase();
     } 

     public void close() 
     {
        dbHelper.close();
     }

     public void createDoctorInfo(String FirstName ,String LastName) 
     {
        ContentValues values = new ContentValues();
        values.put(sqliteHelper.FirstName, FirstName);
        values.put(sqliteHelper.LastName, LastName);

        database.insert(sqliteHelper.TABLE_DoctorInfo, null, values);
     }


}

SECOND CLASS:

public class sqliteHelper extends SQLiteOpenHelper
{
      public static final String TABLE_DoctorInfo = "DoctorInfo";
      public static final String DoctorId = "_id";
      public static final String FirstName = "FirstName";
      public static final String LastName = "LastName";


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

      // Database creation sql statement
      private static final String DATABASE_CREATE = " CREATE TABLE "
      + TABLE_DoctorInfo + "("+DoctorId + " INTEGER PRIMARY KEY AUTOINCREMENT, "
 + FirstName + " TEXT NOT NULL ," +LastName +" TEXT NOT NULL);" ;

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


    @Override
     public void onCreate(SQLiteDatabase database)
    {
        database.execSQL(DATABASE_CREATE);  

    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2)
    {


}

MAIN ACTIVITY:

public class MainActivity extends Activity {

    EditText  fname,lname;
    Button confirm,view;
    dataAccess da=new dataAccess(this);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        da.open();
        fname=(EditText)findViewById(R.id.fname);
        lname=(EditText)findViewById(R.id.lname);
        confirm=(Button)findViewById(R.id.confirm);
        view=(Button)findViewById(R.id.view);

         confirm.setOnClickListener(new View.OnClickListener() {


            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                saveDoctorInfo();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    public void saveDoctorInfo(){

      String fn=fname.getText().toString();
       String ln=lname.getText().toString();


       //save Info into DB
      da.createDoctorInfo(fn,ln);
      //close Conection 
      da.close();
      Toast.makeText(getBaseContext(), "Data Has been saved successfully", Toast.LENGTH_LONG).show();

    }

}

And this is my xml file

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/fnamet"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="41dp"
        android:layout_marginTop="35dp"
        android:text="@string/first_name" />

    <EditText
        android:id="@+id/fname"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/fnamet"
        android:layout_marginLeft="36dp"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:inputType="textPersonName" >

        <requestFocus />
    </EditText>

    <TextView
        android:id="@+id/lnamet"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/fname"
        android:layout_below="@+id/fname"
        android:layout_marginTop="30dp"
        android:text="@string/last_name" />

    <Button
        android:id="@+id/confirm"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/lnamet"
        android:layout_below="@+id/lname"
        android:layout_marginLeft="24dp"
        android:layout_marginTop="50dp"
        android:text="@string/confirm" />

    <Button
        android:id="@+id/view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/confirm"
        android:layout_below="@+id/confirm"
        android:layout_marginTop="36dp"
        android:text="@string/view" />

    <EditText
        android:id="@+id/lname"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/lnamet"
        android:layout_below="@+id/lnamet"
        android:layout_marginTop="18dp"
        android:ems="10"
        android:inputType="textPersonName" />


</RelativeLayout>

Answer 1

how can ensure that my tables are created

By using the convenient open helper. It helps you open a connection to a fully initialized database ( getWritableDatabase ). That includes creating the database from scratch and upgrading the database schema if you need to. The only thing you need to do is to specify what SQL command need to be run in onCreate or onUpgrade .

where can i find my database in android

You should not need to care about the exact path. It's in your app private data directory. DATABASE_NAME = "Medical.db" will - on a typical device - result in
/data/data/your.package.name/databases/Medical.db .

it stores only one record in my tables how can solve such problem

Change the onCreate part. But note that once the database is created the open helper will not try to recreate it. You either need to wipe the app data or need to tell open helper that the version has changed. It will then call onUpgrade which you can use to delete old table definitions / alter them / ...

Answer 2

try to refer the answer in this question, this help a lot in creating database and insert value. LINK