Question

I have tables A and B with identity PKs ida and idb:

ex A:

ida    col1     col2   idb
---------------------------
1      xxxx     foo    NULL
2      yyyy     bar    NULL

ex B:

idb    col3     col4  
----------------------
110    uuuu     rrr  
111    vvvv     ttt   

For each row in A I must insert a row in B. Then i need to update A with the ID’s of the rows I inserted in B while keeping a match between them. There is no other relation between A and B, and no data from A goes into B.

After the insert, B might look like this:

idb    col3     col4  
----------------------
110    uuuu     rrr  
111    vvvv     ttt   
112    aaaa     www    
113    bbbb     mmm    

After the update of A, A will look like this for example:

ida    col1     col2   idb
---------------------------
1      xxxx     foo    112
2      yyyy     bar    113

Now the question is, how do I determine which record from B corresponds to which from A since I have no relations between them? I could insert and update one by one in a loop but for a lot of records this could be problematic.

Is there a way to do this in fewer steps?

Answer 1

Based upon your requirement this is what you can try to achieve the result

  Declare @countA int
  Declare @value int
  set @value =0
  Select @countA=count(*) from TableA

  while @value<@countA
  BEGIN
  Insert into TableB (idb,col3,Col4)
  select max(idb)+1,'aaa','BBBB' from TableB  --I don't know from where you get the values for col3    and col4
  Update TableA
  set idb=(Select max(idb) from TableB) where idb is null and @value+1=ida
  set @value=@value+1
  END