Oracle - to get the constraints on a table

SELECT B.COLUMN_NAME,A.CONSTRAINT_TYPE,A.TABLE_NAME,
B.CONSTRAINT_NAME ,a.*
FROM USER_CONSTRAINTS A,
USER_CONS_COLUMNS B
 WHERE A.TABLE_NAME = B.TABLE_NAME
AND lower(B.CONSTRAINT_NAME) like '%staff%' AND A.CONSTRAINT_NAME = B.CONSTRAINT_NAME and lower(r_constraint_name) like 'pk_staff%'

Oracle - to get the comments on a column

select * from user_col_comments where column_name ='STATUS_FLAG'

oracle to check the locking sessions

select
s1
|| .osuser || ' - ' || s1.MODULE || ' - ' || s1.username '@' || s1.machine || ' ( SID=' || s1.sid || ' ) is blocking '|| s2
|| .osuser || ' - ' || s2.MODULE ' - ' || s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_statusfrom gv$lock l1, gv$session s1, gv$lock l2, gv$session s2where s1.sid=l1.sid and s2.sid=l2.sidand l1.BLOCK=1 and l2.request > 0
and l1.id1 = l2.id1and l2.id2 = l2.id2 ;