import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import java.util.ArrayList;
public class DBHandler extends SQLiteOpenHelper {
// creating a constant variables for our database.
// below variable is for our database name.
private static final String DB_NAME = "coursedb";
// below int is our database version
private static final int DB_VERSION = 1;
// below variable is for our table name.
private static final String TABLE_NAME = "mycourses";
// below variable is for our id column.
private static final String ID_COL = "id";
// below variable is for our course name column
private static final String NAME_COL = "name";
// below variable id for our course duration column.
private static final String DURATION_COL = "duration";
// below variable for our course description column.
private static final String DESCRIPTION_COL = "description";
// below variable is for our course tracks column.
private static final String TRACKS_COL = "tracks";
// creating a constructor for our database handler.
public DBHandler(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
// below method is for creating a database by running a sqlite query
@Override
public void onCreate(SQLiteDatabase db) {
// on below line we are creating
// an sqlite query and we are
// setting our column names
// along with their data types.
String query = "CREATE TABLE " + TABLE_NAME + " ("
+ ID_COL + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ NAME_COL + " TEXT,"
+ DURATION_COL + " TEXT,"
+ DESCRIPTION_COL + " TEXT,"
+ TRACKS_COL + " TEXT)";
// at last we are calling a exec sql
// method to execute above sql query
db.execSQL(query);
}
// this method is use to add new course to our sqlite database.
public void addNewCourse(String courseName, String courseDuration, String courseDescription, String courseTracks) {
// on below line we are creating a variable for
// our sqlite database and calling writable method
// as we are writing data in our database.
SQLiteDatabase db = this.getWritableDatabase();
// on below line we are creating a
// variable for content values.
ContentValues values = new ContentValues();
// on below line we are passing all values
// along with its key and value pair.
values.put(NAME_COL, courseName);
values.put(DURATION_COL, courseDuration);
values.put(DESCRIPTION_COL, courseDescription);
values.put(TRACKS_COL, courseTracks);
// after adding all values we are passing
// content values to our table.
db.insert(TABLE_NAME, null, values);
// at last we are closing our
// database after adding database.
db.close();
}
// we have created a new method for reading all the courses.
public ArrayList<CourseModal> readCourses() {
// on below line we are creating a
// database for reading our database.
SQLiteDatabase db = this.getReadableDatabase();
// on below line we are creating a cursor with query to read data from database.
Cursor cursorCourses = db.rawQuery("SELECT * FROM " + TABLE_NAME, null);
// on below line we are creating a new array list.
ArrayList<CourseModal> courseModalArrayList = new ArrayList<>();
// moving our cursor to first position.
if (cursorCourses.moveToFirst()) {
do {
// on below line we are adding the data from cursor to our array list.
courseModalArrayList.add(new CourseModal(cursorCourses.getString(1),
cursorCourses.getString(4),
cursorCourses.getString(2),
cursorCourses.getString(3)));
} while (cursorCourses.moveToNext());
// moving our cursor to next.
}
// at last closing our cursor
// and returning our array list.
cursorCourses.close();
return courseModalArrayList;
}
// below is the method for updating our courses
public void updateCourse(String originalCourseName, String courseName, String courseDescription,
String courseTracks, String courseDuration) {
// calling a method to get writable database.
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
// on below line we are passing all values
// along with its key and value pair.
values.put(NAME_COL, courseName);
values.put(DURATION_COL, courseDuration);
values.put(DESCRIPTION_COL, courseDescription);
values.put(TRACKS_COL, courseTracks);
// on below line we are calling a update method to update our database and passing our values.
// and we are comparing it with name of our course which is stored in original name variable.
db.update(TABLE_NAME, values, "name=?", new String[]{originalCourseName});
db.close();
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// this method is called to check if the table exists already.
db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
onCreate(db);
}
}