Mate sorry but your question is so confusing 😀

could you explain it

in another fashion.

here is your all three tables

Create Table #A( ENTERPRISE_MAIN_CODE INT , ENTERPRISE_SUB_CODE INT , ENTERPRISE_DESCRIPTION Char )

GO

insert into #a values

(1, 0, 'A'),

(2 ,0, 'B'),

(3 ,0, 'C'),

(4 ,0, 'D'),

(5 ,0, 'E'),

(6 ,0, 'F'),

(7 ,0, 'G'),

(8 ,0, 'H'),

(9 ,0, 'I')

GO

Create TABLE #B ( ID_NO int ,ENTERPRISE_MAIN_CODE int , ENTERPRISE_SUB_CODE int )

GO

insert into #B values

(1, 1 ,1),

(2 ,1 ,2),

(3 ,7, 1),

(4 ,4 ,1),

(5 ,4 ,1 ),

(6 ,6 ,1),

(7 ,6 ,5)

GO

Create TAble #C (ID_NO int, ENTERPRISE_ID_NO int ,ENTERPRISE_DATE bigint , ENTERPRISE_AMT int )

GO

INsert into #C VAlues

(1, 1, 20130109 ,1000),

(1, 2 ,20130315 ,2000 ),

(2 ,3 ,20120120 ,3000),

(2 ,4 ,20120305 ,4000),

(3 ,5 ,20141111 ,5000),

(4 ,6 ,20130115 ,6000),

(5 ,7, 20130320 ,7000)

GO

Select * From #a

Select * From #B

Select * From #C