How to create a database

To create a SQLite database in Android using Java, follow these steps:

1. Create a subclass of SQLiteOpenHelper: The SQLiteOpenHelper class is a helper class in Android that manages database creation and version management.

public class DatabaseHelper extends SQLiteOpenHelper {
    public static final String DATABASE_NAME = "Student.db";
    public static final String TABLE_NAME = "student_table";
    public static final String COL_1 = "ID";
    public static final String COL_2 = "NAME";
    public static final String COL_3 = "MARKS";
    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("create table " + TABLE_NAME +" (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT, MARKS INTEGER)");
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
        onCreate(db);
    }
}

2. Instantiate the helper class: Use the helper class to create and manage the database.

DatabaseHelper myDb = new DatabaseHelper(this);

3. Add data to the database: Use the getWritableDatabase() method to create an instance of the SQLiteDatabase class. Then use its insert() method to add data to the database.

SQLiteDatabase db = myDb.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put("NAME", "John");
contentValues.put("MARKS", 95);
long result = db.insert("student_table", null ,contentValues);

4. Query the database: Use the getReadableDatabase() method to get an instance of the SQLiteDatabase class. Then use its query() method to retrieve data from the database.

SQLiteDatabase db = myDb.getReadableDatabase();
Cursor res =  db.rawQuery( "select * from student_table", null );