SQLite Database Connectivity in Android

Introduction

In this article, we will see how to create a SQLite database in an Android application. We will also see how to add records to the database and read and display in an application.

SQLiteDatabase

In Android, the SQLiteDatabase namespace defines the functionality to connect and manage a database. It provides functionality to create, delete, manage and display database content.

Create a Database

Simple steps to create a database and handle are as following.

1. Create "SQLiteDatabase" object.
2. Open or Create database and create connection.
3. Perform insert, update or delete operation.
4. Create Cursor to display data from table of database.
5. Close the database connectivity.

Following tutorial helps you to create database and insert records in it.

Step 1: Instantiate "SQLiteDatabase" object

SQLiteDatabase db;

Before you can use the above object, you must import the android.database.sqlite.SQLiteDatabase namespace in your application.

db=openOrCreateDatabase(String path, int mode, SQLiteDatabase.CursorFactory factory)

This method is used to create/open database. As the name suggests, it will open a database connection if it is already there, otherwise it will create a new one.

Example,

db=openOrCreateDatabase("XYZ_Database",SQLiteDatabase.CREATE_IF_NECESSARY,null);

Arguments:

String path	Name of the database
Int mode	operating mode. Use 0 or "MODE_PRIVATE" for the default operation, or "CREATE_IF_NECESSARY"  if you like to give option that "if database is not there, create it"
CursorFactory factory	An optional factory class that is called to instantiate a cursor when query is called

Step 2: Execute DDL command

db.execSQL(String sql) throws SQLException

This command is used to execute single SQL statement which doesn't return any data means other than SELECT or any other.

db.execSQL("Create Table Temp (id Integer, name Text)");

In the above example, it takes "CREATE TABLE" statement of SQL. This will create a table of "Integer" & "Text" fields.

Try and Catch block is require while performing this operation. An exception that indicates there was an error with SQL parsing or execution.

Step 3: Create object of "ContentValues" and Initiate it.

ContentValues values=new ContentValues();

This class is used to store a set of values. We can also say, it will map ColumnName and relavent ColumnValue.

values.put("id", eid.getText().toString());         
values.put("name", ename.getText().toString()); 

String Key	Name of field as in table. Ex. "id", "name"
String Value	Value to be inserted.

Step 4: Perform Insert Statement.

insert(String table, String nullColumnHack, ContentValues values)

String table	Name of table related to database.
String nullColumnHack	If not set to null, the nullColumnHack parameter provides the name of nullable column name to explicitly insert a NULL into in the case where your values is empty.
ContentValues values	This map contains the initial column values for the row.

This method returns a long. The row ID of the newly inserted row, or -1 if an error occurred.

Example,

db.insert("temp", null, values);

Step 5: Create Cursor

This interface provides random read-write access to the result set returned by a database query.

Cursor c=db.rawQuery(String sql, String[] selectionArgs)
 

Strign sql	The SQL query
String []selectionArgs	You may include ?s in where clause in the query, which will be replaced by the values from selectionArgs. The values will be bound as Strings.

Example,

Cursor c=db.rawQuery("SELECT * FROM temp",null);

Methods
 

moveToFirst	Moves cursor pointer at first position of result set
moveToNext	Moves cursor pointer next to current position.
isAfterLast	Returs false, if cursor pointer is not at last position of result set.

Example,

c.moveToFirst();
while(!c.isAfterLast())
{
     //statement…
c.moveToNext();
}

Step 6: Close Cursor and Close Database connectivity

It is very important to release our connections before closing our activity. It is advisable to release the Database connectivity in "onStop" method. And Cursor connectivity after use it.

DatabaseDemoActivity.java

package com.DataBaseDemo;

import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class DataBaseDemoActivity extends Activity {
    /** Called when the activity is first created. */
      SQLiteDatabase db;
Button btnInsert;

      @Override
      public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
      btnInsert=(Button)findViewById(R.id.button1);
      try{
      db=openOrCreateDatabase("StudentDB",SQLiteDatabase.CREATE_IF_NECESSARY,null);
      db.execSQL("Create Table Temp(id integer,name text)");
      }catch(SQLException e)
      {
      }
      btnInsert.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
           // TODO Auto-generated method stub
           EditText eid=(EditText) findViewById(R.id.editText1);
           EditText ename=(EditText)findViewById(R.id.editText2);
           ContentValues values=new ContentValues();
           values.put("id", eid.getText().toString());
           values.put("name", ename.getText().toString());
           if((db.insert("temp", null, values))!=-1)
           {
           Toast.makeText(DataBaseDemoActivity.this, "Record Successfully Inserted", 2000).show();
           }
           else
           {
           Toast.makeText(DataBaseDemoActivity.this, "Insert Error", 2000).show();
           }
           eid.setText("");
           ename.setText("");

           Cursor c=db.rawQuery("SELECT * FROM temp",null);
           c.moveToFirst();
           while(!c.isAfterLast())
           {
           Toast.makeText(DataBaseDemoActivity.this,c.getString(0)+ " "+c.getString(1),1000).show();
           c.moveToNext();
           }
           c.close();
           }
        });
    }
    @Override
    protected void onStop() {
      // TODO Auto-generated method stub
      db.close();
      super.onStop();
    }
}

Note:

If you want to see where your database stored? Follow below instruction.

1. Start Your Emulator ( It is necessary to start Emulator to see File Explorer content)
    

2. Open "File Explorer"
   
   
    

3. Data -> Data -> find your "package" -> databases -> "database"

Summary

SQLiteDatabase provide so much functionality to create and manage databases. In this article, we learned how to create a new database, connect to it and read and display data.

Resources

Here are some useful related resources:

• Working With Text Controls in Mono for Android
• RelativeLayout in Android Using Visual Studio 2010
• Passing Data From One Activity to Another Activity in Android
• Working with Tab Layout in Mono For Android