Android :Working with DB

Android :Working with DB

You will be needing 3 user defined class files.

1. File A which extends sqlitehelper (compulsory)
2. File B which contains all methods like - create table,Insert data,Select etc.,
3. File C , for Getter and Setter Class which is more for making your code more classy.

Let File A =sqllitehelperclass
Let File B = DBOperations
Let File C= Persons

sqllitehelperclass.java

public class sqllitehelperclass extends SQLiteOpenHelper

 {

    public sqllitehelperclass(Context context)
    {
        super(context, "test_db", null, 1);
    }
   
    @Override  // onCreate() is only run when the database file did not exist and was just created    

 public void onCreate(SQLiteDatabase db)
    {
        db.execSQL("CREATE TABLE Persons( PersonID INTEGER PRIMARY KEY AUTOINCREMENT,FirstName TEXT, Age INT)");
    }

    @Override  //    onUpgrade() is only called when the database file exists but the stored version number is lower than requested in //constructor.    

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }

}

DBOperations.java

public class DBOperations {
  
    SQLiteOpenHelper sql_helper;
  
    DBOperations(Context context){  
        sql_helper=new sqllitehelperclass(context);
        //Downcasting SQLiteOpenHelper instance with the user defined class "SQLiteOpenHelperclass"
    }
  
    void create_table(){
        sql_helper.getWritableDatabase().execSQL("CREATE TABLE Persons( PersonID INTEGER PRIMARY KEY AUTOINCREMENT,FirstName TEXT, Age INT)");      
        Log.d("db","New db created");
        sql_helper.getWritableDatabase().close();
    }
  
    void delete_table(){
        sql_helper.getWritableDatabase().execSQL("DROP TABLE IF EXISTS Persons");  
        Log.i("db", "database deleted");
        sql_helper.getWritableDatabase().close();
    }

    void insert(){
   //     sql_helper.getWritableDatabase().rawQuery("INSERT INTO Persons (FirstName,Age) VALUES ('Deepak','100');", null);

sql_helper.getWritableDatabase().execSQL("INSERT INTO Persons (FirstName,Age) VALUES ('Deepak','100');");

        sql_helper.getWritableDatabase().close();
    }
  
    List<persons> db_getall_data()
    {  
        int record_count;
        List<persons> query_res=new ArrayList<persons>();

        String[] args={"5P"};
        Cursor resultSet=sql_helper.getReadableDatabase().rawQuery("SELECT * FROM Persons", args);
        Log.d("db", "No of Records present="+String.valueOf(resultSet.getCount()));
        record_count=resultSet.getCount();
        resultSet.moveToFirst();
       
        if(record_count>0){
            while (record_count!=0)
            {
                persons Persons=new persons();
                Persons.put_age(resultSet.getInt(resultSet.getColumnIndex("Age")));
                Persons.put_name(resultSet.getString(resultSet.getColumnIndex("FirstName")));
                query_res.add(Persons);  
                resultSet.moveToNext();
                record_count=record_count-1;
            }
        }      
        sql_helper.getReadableDatabase().close();
        return query_res;
    }
  
  
    public boolean isTableExists()
    {
        try{
            Cursor cursor = sql_helper.getReadableDatabase().rawQuery("select DISTINCT tbl_name from sqlite_master where tbl_name = '"+"Persons"+"'", null);
            Log.d("DB","rows="+cursor.getCount());
            cursor.close();
        }catch(Exception e){
            sql_helper.getReadableDatabase().close();
            Log.d("Db","Table does not exist ");
            return false;
        }
       
        sql_helper.getReadableDatabase().close();
       return true;
    }
  
  }

person.java

public class persons {
   
    int age;
    String name;
   
    int get_age(){
        return age;
    }
   
    String get_name(){
        return this.name;
       
    }
   
    void put_name(String name){
        this.name=name;
       
    }
   
    void put_age(int age){
        this.age=age;
    }
}