Sql server sum over one column with another column as criteria

Question

I have this table

Customer    Date    Revenue
D   20140825    25
F   20130606    53
C   20130315    70
A   20140201    86
H   20140125    18
B   20140408    74
B   20130515    84
G   20130107    0
H   20141218    86
D   20130916    78
E   20140814    38
G   20130304    36
C   20131119    94
F   20131126    48
A   20131014    20
B   20140623    50
H   20141224    60
B   20140305    19
E   20130208    46
F   20140203    55
B   20140813    0
F   20130419    87
B   20131108    28
A   20140609    82
D   20140524    90
B   20130117    19
C   20140610    74
G   20130221    58
H   20140322    85
A   20141210    3
B   20140905    42
B   20131212    4
F   20131003    87
D   20141208    93
D   20140922    36
H   20140113    62
E   20130607    45
E   20140117    8
C   20130205    47
C   20140710    9
D   20140526    95
D   20140718    98
H   20140201    15
B   20140510    49
F   20140316    19
C   20140112    99
A   20130828    31
D   20131017    81
F   20131005    5
H   20140124    16
A   20130405    17
F   20130613    73
E   20130512    97
A   20130915    94
C   20140920    80
B   20130907    53
C   20130621    22
F   20141213    23
H   20140914    21
B   20130620    5
B   20141008    12
G   20130523    87
B   20140506    79
C   20130124    13
B   20130120    91
C   20130328    62
C   20141104    29
H   20130817    85
F   20140105    58
B   20130727    34
A   20140525    20
G   20130103    87
C   20130403    99
H   20140801    24
C   20141001    20
H   20130227    82
C   20131128    43
D   20130503    47
F   20130917    52
C   20130501    21
F   20140305    13
F   20140919    67
D   20140627    16
G   20140222    92
H   20130903    40
B   20140103    98
A   20140816    39

And I want to sum the revenue column starting from the dates in another column of the following table

customer    registrationdate    Sum of Revenue From Registration date till today
A           20140101    
B           20140120    
C           20140201    
D           20131222    
E           20131202    
F           20130102    
G           20131212    
H           20140209

Answer 1

The trick is to join the other table by Customer. Then you can filter out all records where the Date is before the RegistrationDate. The remaining records are grouped and aggregated (sum) to get the total revenue per customer.

select
  r.Customer,
  sum(r.Revenue) as RevenueSinceRegistrationDate
from
  Revenue r
  inner join OtherTable t on t.Customer = r.Customer
where
  r.Date >= t.RegistrationDate  
group by
  r.Customer