The goal is to add a column, which is a result of a select statement, to an existing input data set.
For example, how to add column D to below existing columns A,B,C where column D is a result of a select statement that uses column A B C in the where clause?
To be specific, now we have column A B C as our input dataset,
A B C
1 2 3
given above, how to add column D = select GBQ_D from a good big query table where, for each row, GBQ_A in that table = A, GBQ_B in that table = B, and GBQ_C in that table = C
Let me know if you need further clarification. Thanks so much for your help.
