As per C-23 curriculum there is no rdbms and oops through c++ but we have these subjects in the syllabus you mentioned. How can we prepare for that subjects without having in our curriculums?

Dear student, the core concepts of OOPS and RDBMS are still fundamental to computer science and highly valued by employers. If these subjects are not explicitly covered in your C-23 curriculum, then you may need to prepare for them via self study and self help books.