Is Dropping a column "CHECK" constraint possible?

Hi Folks ,

can anyone please help?
i have a to drop a check contstraint from a column. eg

tradein_clients=# \d t_a
Table "t_a"
Column | Type | Modifiers
------------+---------+-----------
company_id | integer |
exp | text |
imp | text |
Check constraints: "$1" (length(imp) > 1)
"aaaaaq" (length(imp) > 1)

Can i remove to contraints thru ALTER TABLE or similar commands.
I have read the docs for ALTER TABLE but the command described is
not working for me.

=======================================================
ALTER TABLE [ ONLY ] table
DROP CONSTRAINT constraint { RESTRICT | CASCADE }
========================================================

Regards
Mallah.

--
Rajesh Kumar Mallah,
Project Manager (Development)
Infocom Network Limited, New Delhi
phone: +91(11)6152172 (221) (L) ,9811255597 (M)

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