How to capture data in a field from a table then insert them it to a destination table

Question

Environment:
SQL Server 2008 R2
Introduction:
I have three tables. one is staging, the other child, the last one is parent. Both parent and child table have referential integrity
(exam_id) .  The definition of the child table is 
CREATE TABLE [dbo].child
[ind_id] [int] IDENTITY(1,1) NOT NULL,
[exam_dt] [datetime] NULL, exam_id int not null, [sub_cd] [nvarchar](4) NOT NULL,
[score] [varchar](2) NOT NULL,
The parent table has the following definition 
CREATE TABLE [dbo].[parent]
[exam_id] [int] IDENTITY(1,1) NOT NULL,
[pn_id] [char](9) NOT NULL,
[sub_cd] [varchar](3) NULL
when loading 1000 records to the table each record has exam_id generated. 
Problem:
I was able successfully to load data from staging to parent but, How would I load/copy from parent exam_id - identity (1,1 )generated upon loading data - to the destination table (child table)
Please help 

Answer 1

Environment:
SQL Server 2008 R2
Introduction:
I have three tables. one is staging, the other child, the last one is parent. Both parent and child table have referential integrity
(exam_id) .  The definition of the child table is 
CREATE TABLE [dbo].child
[ind_id] [int] IDENTITY(1,1) NOT NULL,
[exam_dt] [datetime] NULL, exam_id int not null, [sub_cd] [nvarchar](4) NOT NULL,
[score] [varchar](2) NOT NULL,
The parent table has the following definition 
CREATE TABLE [dbo].[parent]
[exam_id] [int] IDENTITY(1,1) NOT NULL,
[pn_id] [char](9) NOT NULL,
[sub_cd] [varchar](3) NULL
when loading 1000 records to the table each record has exam_id generated. 
Problem:
I was able successfully to load data from staging to parent but, How would I load/copy from parent exam_id - identity (1,1 )generated upon loading data - to the destination table (child table)
Please help 
I could be misunderstanding your requirements, but I get the feeling you're misunderstood. I can see the exam_id (better named parent_id) acts as a foreign key to exam_id (better named fk_parent_id) in the child table.
Without seeing the data though, it's not immediately obvious how you identify the relationship between the two while loading. When the data is supplied, what is the format of the third, source table? Does this include parent and child as single entries including
a relationship ie normalised data?
I don't know if this is useful or not, but when inserting single records into a table with an identity key:
insert into table1 (col2, col3) select 'text1','text2'
insert into table2 (col2, col3, FK, col5) select 'text1','text2',@@identity, 'text3'
@@identity provides the last inserted value. Obviously for larger scale operations this isn't what you're looking for.
In the event your staging table happened to hold parent, child and a source record ID (identity column in staging, but just a secondary indexed column in the other tables) however, you would have the rather easy job of:
update child
set exam_id = parent.exam_id
from child inner join parent on child.source_id = parent.source_id
Really hard to guess without seeing more