Postgres 15

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CREATE TABLE students (
  enroll_id VARCHAR(20) PRIMARY KEY,
  std_name VARCHAR(24),
  CONSTRAINT valid_enroll_id CHECK (enroll_id ~ '^20\d{2}(CS|EC|MC|CV)\d{3}(D|0)\d{3}$')
);

CREATE TABLE

select * from students;

enroll_id
std_name

SELECT 0

insert into students values('ABC123', 'ABCDEF');

ERROR:  new row for relation "students" violates check constraint "valid_enroll_id"
DETAIL:  Failing row contains (ABC123, ABCDEF).

insert into students values('2021CS213D011', 'ABCDEF');

INSERT 0 1

Select * from students;

enroll_id
std_name

2021CS213D011
ABCDEF

SELECT 1