Putting constraint in Oracle

how to put following constraint in any column of the table.?

total number of char not to exceed 5,
first char must be 'D',
second char can be 'E','H' or 'T',
and 3rd, 4th, 5th char must be digits.[0-9].

for ex following are valid values : DE001, DH123, DT345 etc.

I tried this..
create table disk_tab(disk_id varchar2(5) constraint disk_name1 check (disk_id like ('D[EHT][0-9][0-9][0-9]')), disk_name char(10));

table is created but the "disk_name1" constraint is violated whenever m trying to insert values such as DE123, DH001 etc..

abhishek this kind of problem is caused due to incorrect expression we cannot use normal regular expressions with the CHECK like command hence try the following condition

CHECK( disk_id LIKE 'DE___' OR disk_id LIKE 'DH___' OR disk_id LIKE 'DE___')

'_' can take any character. he wants 3 last characters to be numbers.??

CREATE TABLE name_tab(NAME VARCHAR2(5),CONSTRAINT name_num check((name like 'DE___' or name like 'DH___' or name like 'DH___') and (substr(name,3,5) between 0 and 999)));

ya... it works...

if u apply a constraint like this "check (disk_id like 'DE[0-9][0-9][0-9]' or disk_id like 'DH[0-9][0-9][0-9]' or disk_id like 'DT[0-9][0-9][0-9]');" on a column called disk_id, the constraint is applied without showing any error... my question is what input will satisfy the above constraint? i have tried for input like "dh123" but this violates the constraint...

thnks frnds.. its working.. keep solving my probs.

@ shivangi shah
it will accept "DE[0-9][0-9][0-9]","DH[0-9][0-9][0-9]" and "DT[0-9][0-9][0-9]". no significance of using square brackets and specifying range. it takes everything as characters.

yeah ok...thnks..