SAP ABAP Program to insert data into custom table zstudent from selection screen

 Program: 

*&---------------------------------------------------------------------*
*& Report ZINSERT
*&---------------------------------------------------------------------*
REPORT ZINSERT.

TABLES: zstudent.

PARAMETERS:
  p_id   TYPE zstudent-id,
  p_name TYPE zstudent-name,
  p_roll TYPE zstudent-roll,
  p_age  TYPE zstudent-age.

START-OF-SELECTION.

  DATA: lv_student_id TYPE zstudent-id,
        ls_student    TYPE zstudent.

  SELECT SINGLE *
    INTO @ls_student
    FROM zstudent
    WHERE id = @p_id.

  IF sy-subrc = 0.
    write: 'Student ID already exists!'.
  ENDIF.

  ls_student-id   = p_id.
  ls_student-name = p_name.
  ls_student-roll = p_roll.
  ls_student-age  = p_age.

  INSERT zstudent FROM ls_student.

  IF sy-subrc = 0.
    write: 'Student inserted successfully!'.
  ELSE.
    write: 'Insert failed!'.
  ENDIF.

       Output: