Download SQLITE TUTORIAL in android

Introduction: Most of the applications require the data to be saved and loaded when it is
demanded. As we see in games that whole game is saved and later on this is loaded again. You
also want to store user preferences so that user may customize application and store data
entered by the user.
Android Methods for saving data
Shared Preferences: When you want a limited application data such as user preferences related
to application UI, you prefer to store data using Shared Preferences. In this method you store
data as key values pairs.
Files: In android you are allowed to create and read/write to files. You can create files on the
internal or external media of the device.
SQLite Database: Android also facilitates to work with relational database system. The
Database system used in android is SQLite Database system.
Content Provider: Content Providers let you expose a well-defined interface for using and
sharing private data. You can control access to Content Providers using the standard permission
system.
Here we are going to discuss how SQLite database is used to save data in android. Firstly, let’s
have a brief introduction about SQLite database system.
SQLite Database
SQLite database is a




Zero configuration (as it is default database provided embedded in android so no
configuration is required)
Lightweight ( requires minimum memory)
Open source (no license)
Single database file (Only one file is made against one database)
If an application creates a database it is stored in following directory
DATA/data/APP_NAME/databases/FILENAME.
Before starting to work with database let’s discuss essential concepts which can help in
understanding the topic.
1. SQL: SQL is a structured query language that is used for database manipulation. It
provides simple queries to create and manipulate database system. Let’s start from data
retrieval using SQL.
1.1 Select statement
Select statement is used to get data from database system. The syntax of using
select statement is as follow.
Select col1,col2….coln From TableName where some condition order by column
E.g. select rollno from students where name=’Asad’
To get all columns of a table use * as select * from students
1.2 Data Definition
1.2.1 create table
This statement is used to create a new table if it does not exist. The syntax is
as follow.
CREATE TABLE newtable(
Col1 INT,
Col2 VARCHAR(50),
col3 DATE NOT NULL,
PRIMARY KEY (col1, col2)
);
Example: create table users (uid int primary key, password varchar(50));
1.2.2 Drop table
This statement is used to drop a table from database system if it exist.
Syntax is as follow.
Drop table tablename
Example: drop table users
1.2.3 Alter table
Alter table statement is used to update table definition.
Syntax is as follow:
Update table tableName Add columnName type;
Example: Update table users Add age int;
1.3 Data Manipulation
1.3.1 Insert statement
Insert statement is used to add records in database system.
Syntax is as follow:
Insert into tablename(col1,col2,…,coln) values(v1,v2,…vn);
Example: insert into users(uid,password) values(12,’abcd123’);
1.3.2 Delete statement
Delet statement is used to delete records in database system.
Syntax is as follow:
Delete from tablename where somecondition;
Example: Delete from users where uid=12;
Delete from users will delete all records from database.
1.3.3 update statement
Update statement is used to update records in database system
Syntax is as follow:
Update table tableName set col1=v1 where col2=v2
Example: Update table users set password=’6t8979’ where uid=12
2. Packages to use SQLite Database
Following packages are used to work with SQLite Database system
 android.database
 android.database.sqlite
3. SQLiteopenHelper
To create and upgrade database in our application we need a class that extends
SQLiteOpenHelper class. To use it we have to override two abstract methods onCreate()
and onUpgrade(). SQLiteOpenHelper provides following methods:
onCreat(): this method is called when database does not exist.
onUpgrade(): this method allow you to update or alter database schema.
getReadableDatabase(): create or/and open a database for only data reading.
getWriteableDatabase():create or/and open a database for both data reading and
writing.
close(): close the database if it is opened.
onOpen(): this method is called when a database is opened.
4. ContentValues
ContentValues is a data structure used to store key and corresponding values. Keys
represent columns in database and values are their values. This is helpful for inserting
and updating records in database.
5. SQLiteDataBase class
This is base class to work with database system. This class has methods to manage
database. It provides useful methods to insert a record delete a record and update a
record in a database. All manipulation of database is done through this class. Some most
commonly used methods of this class are given bellow:
insert(String tableName, String nullColumnHack, ContentValues contentValues);
this method is used to insert a record in a database table.
delete(String table, String whereClause, String[] whereArgs)
this method is used to delete a record from database table.
update (String table, ContentValues contentValues,String whereClause, String[] whereArgs)
this method is used to delete a record from database table.
this method is used to select records from database table and return cursor object. we
will learn cursor a little bit later.
<Example:rawQuery("select * from users where uid = ?", new String[] { id });
query(String table, String[] columns, String selection, String[] Args, String
groupByClause, String havingClause, String orderByClause, String
NoOfRowsToBeFethed)
this method executes given query and return cursor object.
6. Cursor
Cursor is just like ResultSet in java. It contains all the records retrieved in form of result
of a query. Cursor has number of methods to manipulate returned data. Some of them
are as follow:
MoveToNext()
Move cursor to next record
MoveToPrevious()
Move cursor to previous record
MoveToFirst()
Move cursor to first record
MoveToLast()
Move cursor to last record
MoveToPosition(int p)
Move cursor to a record at given position
isFirst()
Returns true if it is first record
isLast()
Returns true if it is last record
getString(int columnIndex)
Return String stored at given column of a row
getInt(int columnIndex)
Return integer value stored at given column of a row
getDouble(int columnIndex)
Return double value stored at given column of a row
Creating an application that explain working with database
In this example I have made 5 activities first is main activity and a DataBase helper class named
as DBCreator and a student class as Data Transfer Object(DTO) and a DAO class that interact with
database.
Let’s start with class DBCreater. code is given below:
package com.mujadid001;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DBCreator extends SQLiteOpenHelper
{
// constatns to refer database file, table name and datbase version
public static final String student_TABLE_NAME = "Student";
public static final String DATABASE_NAME = "studentsResults.db";
private static int DATABASE_VERSION = 1;
// constructor it only calls super class constructor
public DBCreator(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
// TODO Auto-generated constructor stub
}
// onCreat() method is called to create database first time
@Override
public void onCreate(SQLiteDatabase db)
{
// sql query to create a table
String sql = "CREATE TABLE " + student_TABLE_NAME + " (studentId INTEGER
PRIMARY KEY AUTOINCREMENT, studentName TEXT,Marks INTEGER);";
// Logging a tag for debugging purposes
Log.d(DATABASE_NAME, "oncreate"+sql);
//executing sql query
db.execSQL(sql);
}
//onupgrade() method definition
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
// sql query to drop an existing table normally here alter table query is written but it is
just an example
db.execSQL("DROP TABLE IF EXISTS " +student_TABLE_NAME + ";");
// Logging a tag for debugging purpose
Log.d(DATABASE_NAME, "onupdate");
//now calling onCreate to create table again
onCreate(db);
}
}
Explaination
Constructor : it is used to create an object of this class and call constructor of super class
onCreate() : onCreate() is called by android framework when we call getWritableDatabase() or
getReadableDatbase() methods. it is called when database file is not present.
onUpgrade() : it is called whenever a new version of datbase become available such that definition
of database is changed, a new column has been added, datatype of a column is changed etc.
student Class
package com.mujadid001;
public class student
{
// data memebers
private int id;
private String Name;
public int marks;
// constructors
public student(String name, int marks)
{
Name = name;
this.marks = marks;
}
public student(int id, String name, int marks)
{
super();
this.id = id;
Name = name;
this.marks = marks;
}
// setters and getters
public int getId() {
return id;
}
public void setId(int id)
{
this.id = id;
}
public String getName()
{
return Name;
}
public void setName(String name)
{
Name = name;
}
public int getMarks()
{
return marks;
}
public void setMarks(int marks)
{
this.marks = marks;
}
}
Explanation: student class is self explanatory. it has member variables, getters , setters,
construtors.
DAO CLASS
package com.mujadid001;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
// DAO class
public class DAO
{
// an object of class SQLiteDatabase which have built in functions to manipulate database
SQLiteDatabase db;
//creating a reference of class DBCreator
DBCreator dbcreator;
// creating an object of type Context
Context context;
// constructor
public DAO(Context context)
{
// initializing data members
dbcreator=new DBCreator(context);
// getting writable datbase from class DBCreator. this method is inherited in
DBCreator from its parent
db=dbcreator.getWritableDatabase();
}
// method to insert a record
public int InsertRecord(student s)
{
try
{
//sql query to insert a record
String sql="inser"+DBCreator.student_TABLE_NAME+"(studentName,Marks)
values('"+s.getName()+"',"+s.getMarks()+" );";
//executing sql query
db.execSQL(sql);
return 1;
}
catch(Exception e)
{
// logging if any exception occurs.
Log.e("DB", e.toString()+" DAO.Insert");
return -1;
}
}
// method to delete a record
public int DeleteRecord(int id)
{
try
{
// using built in delete function of class SQLitDatabase
return db.delete(DBCreator.student_TABLE_NAME, "studentId=?", new
String[]{""+id});
}
catch(Exception e)
{
// logging if any exception occurs.
Log.e("DB", e.toString()+" DAO.delete");
return -1;
}
}
public int UpdateRecord(student s)
{
try
{
// creating an object of type ContentValues (explained already in tutorial)
ContentValues values=new ContentValues();
// storing kay value pairs in it
values.put("studentName", s.getName());
values.put("marks", s.getMarks());
// calling built in update function of class SQLitDatabase
return db.update(DBCreator.student_TABLE_NAME, values, "studentId=?",
new String[] {String.valueOf(s.getId())});
}
catch(Exception e)
{
// logging if any exception occurs.
Log.e("DB", e.toString()+" DAO.UpdateRecord");
return -1;
}
}
// getting all records
public Cursor GetRecords()
{
// now I have used rawQuery function of class SQLitDatabase
Cursor c=db.rawQuery("select * from "+DBCreator.student_TABLE_NAME,null);
//returning an object of class Cursor(explained already in tutorial)
return c;
}
//closing databse
public void close()
{
db.close();
}
}
activity_main.xml
<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"
tools:context=".MainActivity" >
<!-- creating a button -->
<Button
android:id="@+id/add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginTop="43dp"
android:layout_weight="1"
android:text="@string/Add"
android:onClick="onClick"
/>
<!-- creating a button
-->
<Button
android:id="@+id/remove"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/add"
android:layout_alignBottom="@+id/add"
android:layout_alignParentRight="true"
android:layout_marginRight="25dp"
android:text="@string/remove"
android:onClick="onClick"
/>
<!-- creating a button
-->
<Button
android:id="@+id/select"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/add"
android:layout_marginTop="50dp"
android:text="@string/select"
android:onClick="onClick"
/>
<!-- creating a button
-->
<Button
android:id="@+id/update"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/select"
android:layout_alignBottom="@+id/select"
android:layout_alignRight="@+id/remove"
android:text="@string/update"
android:onClick="onClick"
/>
</RelativeLayout>
MainActivity.java
package com.mujadid001;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
public class MainActivity extends Activity implements OnClickListener{
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
// onclick method to handle click event of buttons
@Override
public void onClick(View view)
{
switch(view.getId())
{
case R.id.add:
//creating an intent to goto activity to add a new record
Intent it=new Intent(MainActivity.this,AddActivity.class);
//starting new activity
startActivity(it);
break;
case R.id.remove:
//creating an intent to goto activity to select all records
it=new Intent(MainActivity.this,DeleteActivity.class);
//starting new activity
startActivity(it);
break;
case R.id.select:
//creating an intent to goto activity to delete a record
it=new Intent(MainActivity.this,SelectActivity.class);
//starting new activity
startActivity(it);
break;
case R.id.update:
//creating an intent to goto activity to update a record
it=new Intent(MainActivity.this,UpdateActivity.class);
//starting new activity
startActivity(it);
break;
}
}
}
Explanation:MainActivity is very simple it has only one clickListener method onClick to handle click
events. an intent to desired activity is created and activity is started.
Activity_add.xml
<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"
tools:context=".AddActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="@string/sname" />
<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_below="@+id/textView1"
android:ems="10"
android:inputType="textPersonName" >
<requestFocus />
</EditText>
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/editText1"
android:text="@string/marks" />
<EditText
android:id="@+id/editText2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignRight="@+id/textView1"
android:layout_below="@+id/textView2"
android:ems="10"
android:inputType="numberDecimal"/>"
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/editText2"
android:layout_alignBottom="@+id/editText2"
android:layout_marginLeft="35dp"
android:layout_toRightOf="@+id/textView2"
android:onClick="onClick"
android:text="@string/submit" />
</RelativeLayout>
AddActivity.java
package com.mujadid001;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.Toast;
public class AddActivity extends Activity implements OnClickListener
{
//data members
String name;
int marks;
student s;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_add, menu);
return true;
}
// overriden onClick method called when button is clicked
@Override
public void onClick(View v)
{
//getting value of editText Field
String temp=((EditText)findViewById(R.id.editText2)).getText().toString();
// parsing it into integers
marks=Integer.parseInt(temp);
//getting value of editText Field
name=((EditText)findViewById(R.id.editText1)).getText().toString();
//creating an DTO object of type student
s=new student(name,marks);
// creating an object of DAO class
DAO dao=new DAO(AddActivity.this);
// calling its method insert
int i=dao.InsertRecord(s);
// checking if return value is +ve then its mean a record is inserted else an
error has occured
if(i>0)
Toast.makeText(getApplicationContext(), "1 record has been
added", Toast.LENGTH_LONG).show();
else
Toast.makeText(getApplicationContext(), "record has not been
added", Toast.LENGTH_LONG).show();
//finishing this activity
finish();
}
}
Explanation: in activity_add.xml we have two edittext and a button. when a button is clicked
we get value of edit text field and make an object of class students and call method of DAO
class insertRecord() when a record is inserted, a message is displayed and activity is
finished.
DELETE A RECORD
activity_ delete.xml
<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"
tools:context=".DeleteActivity" >
<EditText
android:id="@+id/idfield"
android:layout_width="50dp"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:ems="10"
android:hint="id"
android:inputType="number" >
<requestFocus />
</EditText>
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:onClick="onClick"
android:text="@string/submit" />
</RelativeLayout>
DeleteActivity.java
package com.mujadid001;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.Toast;
public class DeleteActivity extends Activity implements OnClickListener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_delete);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_delete, menu);
return true;
}
@Override
public void onClick(View v)
{
//getting value of editText Field
String id=((EditText)findViewById(R.id.idfield)).getText().toString();
// parsing it into integers
int deleteID=Integer.parseInt(id);
// creating an anonymous object of DAO class and calling deleteRecord
method
int i=new DAO(DeleteActivity.this).DeleteRecord(deleteID);
// checking if return value is +ve then its mean record has deleted else an
error has occured
if(i>0)
Toast.makeText(getApplicationContext(), i+" record has been
deleted", Toast.LENGTH_LONG).show();
else
Toast.makeText(getApplicationContext(), "no record has added",
Toast.LENGTH_LONG).show();
finish();
}
}
Explanation: in delete_activity.xml we have one edittext and a button. when a button is clicked we
get value of edit text field and call method of DAO class DeleteRecord() when a record is deleted, a
message is displayed and activity is finished.
UPDATE A RECORD
activity_ update.xml
<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"
tools:context=".UpdateActivity" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="@string/prompt" />
<EditText
android:id="@+id/marksPrompt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/nameprompt"
android:layout_marginTop="19dp"
android:ems="10"
android:hint="enter marks"
android:inputType="phone" >
<requestFocus />
</EditText>
<EditText
android:id="@+id/idfield2"
android:layout_width="60dp"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginLeft="14dp"
android:layout_toRightOf="@+id/nameprompt"
android:ems="10"
android:hint="id"
android:inputType="phone" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/marksPrompt"
android:layout_marginTop="56dp"
android:layout_toRightOf="@+id/textView1"
android:onClick="onClick"
android:text="@string/submit" />
<EditText
android:id="@+id/nameprompt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/idfield2"
android:ems="10"
android:hint="Enter new name"
android:inputType="textPersonName" />
</RelativeLayout>
UpdateActivity.java
package com.mujadid001;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.EditText;
import android.widget.Toast;
public class UpdateActivity extends Activity implements OnClickListener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_update);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_update, menu);
return true;
}
@Override
public void onClick(View v)
{
//getting value of editText Field
String id=((EditText)findViewById(R.id.idfield2)).getText().toString();
// parsing it into integers
int ID=Integer.parseInt(id);
String mark=((EditText)findViewById(R.id.marksPrompt)).getText().toString();
// parsing it into integers
int marks=Integer.parseInt(mark);
//getting value of editText Field
String name=((EditText)findViewById(R.id.nameprompt)).getText().toString();
//creating an DTO object of type student
student s=new student(ID,name,marks);
// creating an object of DAO class
DAO dao=new DAO(UpdateActivity.this);
// calling its method updateRecord
int i=dao.UpdateRecord(s);
// checking if return value is +ve then its mean a record is updated else an error has occured
if(i>0)
//displaying message
Toast.makeText(getApplicationContext(), "1 record has been updated",
Toast.LENGTH_LONG).show();
else
Toast.makeText(getApplicationContext(), "no record has added",
Toast.LENGTH_LONG).show();
finish();
}
}
Explanation: in update_activity.xml we have three edittext fields and a button. when a button is
clicked we get value of all edit text fields, make an object of class student and call method of DAO
class UpdateRecord() when a record is updated, a message is displayed and activity is finished.
Displaying all records
activity_select.xml
<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"
tools:context=".SelectActivity" >
<ListView
android:id="@+id/list1"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
></ListView>
</RelativeLayout>
SelectActivity.java
package com.mujadid001;
import java.util.ArrayList;
import android.os.Bundle;
import android.app.Activity;
import android.database.Cursor;
import android.view.Menu;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class SelectActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_select);
// getting reference to listview
ListView lv=(ListView) findViewById(R.id.list1);
// creating an object of type ArrayList
ArrayList<String> al=new ArrayList<String>();
// creating an anonymous object of DAO class and calling getRecords method and
storing in Cursor object
Cursor c=new DAO(this).GetRecords();
// Adding all records in cursor into arraylist object
while(c.moveToNext())
{
//getting integer value of first column
int id=c.getInt(0);
//getting string value of 2nd column
String name=c.getString(1);
//getting integer value of 3rd column
int marks=c.getInt(2);
//adding them in to array list
al.add(""+id+" "+name+" "+marks);
}
// creating an array adapter
ArrayAdapter<String> adapter=new
ArrayAdapter(this,android.R.layout.simple_list_item_1,al);
//setting adapter to list
lv.setAdapter(adapter);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_select, menu);
return true;
}
}
Explanation : In select_acticty.xml we have only a listView. in java class we get reference to this
listview.
After that we make an object of arraylist of type string. we create an object of DAO class and called
method getRecords(). which returns a cursor object. we received cursor object an iterate over it to
get all records and save them in arrayList. then we made an object of type arrayAdapter and then
set it to list.
Sample OutPut