Comparing data and updating spreadsheets

[Guest]

I have two spreadsheets with Last Name and First Name columns. What I would
like to do is compare the Last Name and First Name fields in Spreadsheet A to
the same fields in Spreadsheet B. If there's a match, I would like to take
the UserID from Spreadsheet A and update the UserID column in Spreadsheet B.
What is the easiest way to accomplish this?

 

[Guest]

when you say update the User ID on sheet two, is there an existing number
which will be changed. if so, I would add a new column with the old IDs on
sheet two and add a new IDcolumn wit
=if(iserror(sumproduct(--(Sh1!Lastrange=last),--(Sh1!firstrange=first))),oldid,sumproduct(--(Sh1!Lastrange=last),--(Sh1!firstrange=first),Sh1!IDrange))
with the appropriate cells a

 

[Guest]

Whoops! What I want to do is update the UserID column in Spreadsheet B if the
names match and the UserID in Spreadsheet B is blank.

 

[Guest]

Trythe previous recommendation and changing the equation t
=if(and(oldid="",not(iserror(sumproduct(--(Sh1!Lastrange=last),--(Sh1!firstrange=first)))),sumproduct(--(Sh1!Lastrange=last),--(Sh1!firstrange=first),Sh1!IDrange),oldid)

I would add the step of copying the newid and paste special values over the
oldid range before new data is added to Sh1!