Tracking History in ODS

Hi, All.

I have 2 ODS:

ZODS_PAY

Doc_Num   Date           TCode     Amt        
Doc_1        01.11.2008    001      100$      
Doc_1        04.11.2008    001      200$      
Doc_2        07.11.2008    002      300$

ZODS_ACCRUALS

Doc_Num      Date       TCode   Accrued_Amt_Per_Day        
Doc_1        01.11.2008    002      10$ 
Doc_1        02.11.2008    002      10$ 
Doc_1        03.11.2008    002      10$ 
Doc_1        04.11.2008    002      20$                  
Doc_1        05.11.2008    002      20$      
Doc_1        06.11.2008    002      20$      
Doc_2        07.11.2008    002      30$  

I should get the following report:

Doc_Num   Data            Amt    Total_Accrued_Per_Period
Doc_1        01.11.2008   100$        30$ 
Doc_1        04.11.2008   200$        60$ 
Doc_2        07.11.2008   300$        30$ 

My decision is:

1. Create ZODS_PAY2 with following structure:

 Doc_Num   Date          TCode    Amt       ValidFrom    ValidTo 
Doc_1        01.11.2008    001      100$      01.01.2008    03.11.2008 
Doc_1        04.11.2008    001      200$      04.11.2008    31.12.9999 
Doc_2        07.11.2008    002      300$      07.11.2008    31.12.9999

So I understand that I should realize the following algorithm for filling ValidFrom and ValidTo fields:

1. ValidFrom = Date.

2. ValidTo = (Date - 1) if this is a New Record.

After this I should fill a ValidDate to accruals table:

Doc_Num      Date       TCode   ValidDate      Accrued_Amt_Per_Day        
Doc_1        01.11.2008    002    01.01.2008   10$ 
Doc_1        02.11.2008    002    01.01.2008   10$ 
Doc_1        03.11.2008    002    01.01.2008   10$ 
Doc_1        04.11.2008    002    04.11.2008   20$                  
Doc_1        05.11.2008    002    04.11.2008   20$      
Doc_1        06.11.2008    002    04.11.2008   20$      
Doc_2        07.11.2008    002    07.11.2008   30$  

Any ideas? May be my decision is not good. Plz, help me to realize filling time-dependent fields for ODS.