Working With Database in Android

In this Post I will discuss about creating your own database and writing  functions for Insertion, Deletion and Updation of Data in Table.

DataBaseHelper:

We will use  SQLiteOpenHelper  class and extend this class
and overside the methods  onCreate, onUpgrade

public class DataBaseHelper extends SQLiteOpenHelper
{
            public DataBaseHelper (Context context, String name,CursorFactory factory, int version)
            {
                       super(context, name, factory, version);
            }
            // Called when no database exists in disk and the helper class needs
            // to create a new one.
            @Override
            public void onCreate(SQLiteDatabase _db)
            {
                     // statement to create the Table
                    _db.execSQL(SMSBlockerDataBaseAdapter.DATABASE_CREATE);
                   
            }
            // Called when there is a database version mismatch meaning that the version
            // of the database on disk needs to be upgraded to the current version.
            @Override
            public void onUpgrade(SQLiteDatabase _db, int _oldVersion, int _newVersion)
            {
                    // Log the version upgrade.
                    Log.w("TaskDBAdapter", "Upgrading from version " +_oldVersion + " to " +_newVersion + ", which will destroy all old data");
           
           
                    // Upgrade the existing database to conform to the new version. Multiple
                    // previous versions can be handled by comparing _oldVersion and _newVersion
                    // values.
                    // The simplest case is to drop the old table and create a new one.
                    _db.execSQL("DROP TABLE IF EXISTS " + "SMSTABLE");
                    // Create a new one.
                    onCreate(_db);
            }
           
}

SMSBlockerDataBaseAdapter

We create a DataBaseAdpater class and write the functions  for following tasks

• to Open the database
• to close the database
• to insert a new Row/Record in Database
• to delete one or more Records in Database
• to update the database

In the example Code given below  I have created  a Table to store SMSes with following Columns

Id:   Primary Key of the Table
Sender Name:  Name of SMS Sender
Sender Number:  Phone Number of the Sender
Time:  date and time (In Miliseconds) at which SMS is received

Inserting  a new Record in table

To Insert  a new Record in Table  we need to create an Object of ContentValues  class and put the Values in this  like:

ContentValues newValues = new ContentValues();
                // Assign values for each row.
                newValues.put("COLUMN_NAME1", values);
              newValues.put("COLUMN_NAME2", values);

            and so on
then

// Insert the row into your table
                db.insert("TABLENAME", null, newValues);

Deleting a Record from Table

we can delete a row from the Table with delete method
delete("TABLE ANME",String where, String[]  valuesForWhere)

for Ex:
String where="ID=?";
                int numberOFEntriesDeleted= db.delete("BLOCKEDSMSTABLE", where, new String[]{ID}) ;

will delete the Record containing IDs in  new String[]{ID}  array.

To get All the Record in the Table

public Cursor getAllEntries ()
        {
             
                return db.query("BLOCKEDSMSTABLE", null,null, null, null, null, "TIME DESC");
        }

TIME DESC    will fetch in descending order of Time , Pass null to fetch in Ascending Order because by Deafault it fetches in ascending Order

To get 1 or more records depending on Some Condition

Task task=new Task();
                Cursor cursor=db.query("BLOCKEDSMSTABLE", null, " ID=?", new String[]{ID}, null, null, null);

"ID=?"       at RunTime ?  will be replaced by string in the Array OF String passed as 4th parameter
the above query will fetch all the records containing the IDs in String Array(4th parameter)


Updating The Table 

Updating is little similar to Inserting  a record in Table
to update the table we need to create an Object of  ContentValues  and put the new Values in ContentValues object

ContentValues updatedValues = new ContentValues();
                // Assign new values for each row.

                updatedValues.put("TIME", taskToBeUpdated.time);
                updatedValues.put("MESSAGE",taskToBeUpdated.message);
                updatedValues.put("RECIPIENTNUMBER",taskToBeUpdated.recipientNumber);
                updatedValues.put("RECIPIENTNAME", taskToBeUpdated.recipientName);
               
               
                String where="ID = ?";
                db.update("SMSTABLE",updatedValues, where, new String[]{ID});

You can Modify the where variable as per your requirement  like where "EMP_ID="  etc.

How to use this DataBaseAdapter Class  in Activities

Create an Instance of  DataBaseAdapter
Open the DataAbse
Call the Functions/Methods

See The Code :

SMSSchedulerDataBaseAdapter  smsSchedulerDataBaseAdapter =new SMSSchedulerDataBaseAdapter(this);
                    smsSchedulerDataBaseAdapter=smsSchedulerDataBaseAdapter.open();
smsSchedulerDataBaseAdapter.insertEntry(yourParameter);
smsSchedulerDataBaseAdapter.getAllEntries();

The Complete Code :

public class SMSBlockerDataBaseAdapter
{
         // Name of the database
        static final String DATABASE_NAME = "SMSBLOCKERDATABASE.db";

        // database version  if creating first time it should be 1      
        static final int DATABASE_VERSION = 1;

        public static final int NAME_COLUMN = 1;
        // TODO: Create public field for each column in your table.
        // SQL Statement to create a new database.
        static final String DATABASE_CREATE = "create table BLOCKEDSMSTABLE " +
                                         "( " +"ID integer primary key autoincrement,MESSAGE text, SENDERNUMBER text, SENDERNAME text, TIME integer ); ";
                                         
        // Variable to hold the database instance
        public  SQLiteDatabase db;
        // Context of the application using the database.
        private final Context context;
        // Database open/upgrade helper
        private DataBaseHelper dbHelper;
       
        public SMSBlockerDataBaseAdapter(Context _context)
        {
                context = _context;
                dbHelper = new DataBaseHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
        }
       
          // Open the Database
        public SMSBlockerDataBaseAdapter open() throws SQLException
        {
                db = dbHelper.getWritableDatabase();
                return this;
        }


         // Close the Database       
        public void close()
        {
                db.close();
        }
   
        public  SQLiteDatabase getDatabaseInstance()
        {
                return db;
        }
   
    // to Insert A record in Table
        public void insertEntry(Task taskToInsert)
        {
                // TODO: Create a new ContentValues to represent the row
                // and insert it into the database.
                ContentValues newValues = new ContentValues();
                // Assign values for each row.
                newValues.put("MESSAGE", taskToInsert.message);
                newValues.put("SENDERNUMBER",taskToInsert.senderNumber);
                newValues.put("SENDERNAME", taskToInsert.senderName);
                newValues.put("TIME",taskToInsert.time);
                               
               
                // Insert the row into your table
                db.insert("BLOCKEDSMSTABLE", null, newValues);
               
       
        }
        public int deleteEntry(String ID)
        {
               
           
                String where="ID=?";
                int numberOFEntriesDeleted= db.delete("BLOCKEDSMSTABLE", where, new String[]{ID}) ;
              
                return numberOFEntriesDeleted;
               
        }
       
        public void deleteOlderEntries()
        {
                  String olderTime=String.valueOf(new GregorianCalendar().getTimeInMillis()-7*24*60*60*1000);
                  String where="TIME < ?";
                  int numberOFEntriesDeleted= db.delete("BLOCKEDSMSTABLE", where, new String[]{olderTime}) ;
                  Toast.makeText(context, "Number Of Entries Deleted "+numberOFEntriesDeleted, Toast.LENGTH_LONG).show();
        }
        public Cursor getAllEntries ()
        {
              
                return db.query("BLOCKEDSMSTABLE", null,null, null, null, null, "TIME DESC");
        }
       
        public Task getSinlgeEntry(String ID)
        {
               
                Task task=new Task();
                Cursor cursor=db.query("BLOCKEDSMSTABLE", null, " ID=?", new String[]{ID}, null, null, null);
                if(cursor.getCount()==0)
                {
                   
                    return null;
                }
                cursor.moveToFirst();
                task.id= cursor.getString(cursor.getColumnIndex("ID"));
                task.message = cursor.getString(cursor.getColumnIndex("MESSAGE"));
                task.senderNumber = cursor.getString(cursor.getColumnIndex("SENDERNUMBER"));
                task.senderName = cursor.getString(cursor.getColumnIndex("SENDERNAME"));
                task.time = Long.parseLong(cursor.getString(cursor.getColumnIndex("TIME")));
                task.reason=cursor.getString(cursor.getColumnIndex("REASON"));
                //Log.i("getSingle Entry ID: "+"PhoneNumber "+task.senderName+"  "+task.message,ID);
                cursor.close();
                return task;
        }
}