sys_guid using Execute Sql Task

Hi Everyone,

i have column   name : DATA_U(target)  which is an unqiue constraint column , here

my requirement is i want to assign a unique value i.e, SYS_GUID() value to this column

for this i have took a Global  variable with string Datatype,

in Execute Sql Task:

sql query is:

SELECT RAWTOHEX (SYS_GUID())as DATA_U FROM DUAL

this i am assign to global variable .now  i am using this variable inside  derived column,  assign to that column.

But above mentioned query generates  value which is same  for every row., first record will enter , next  value is same,this column is unique so it will not accept same value into this.

error message is :

[Oracle Destination [487]] Error: OCI error encouneterd. ORA-00001: unique constraint (SYSSS.SYS_C00295113) violated

i can make use of script component  :
http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/86c375c2-98fa-4fc3-b9be-2e11aa1aacdd

but i want to make use of Execute sql Task, with variable, then this variable can be used in different dataflow task, because when ever i am using script component it is taking some time to load. is this possible to make use of Execute sql Task.

Please Suggest me.

karteek_miryala