Question

Select from table where data row missing

SELECT statement, Outer Join

I have a table with the main fields being BU, ASSET, BOOK
for any BU and ASSET combination, there should be two to four rows of data, with just the BOOK value being different. Data corruption has caused us to find all BU-ASSET combinations missing the value 'AMT' for BOOK. I need to join the table to itself (I think) to do this, but my repeated efforts have failed. If I have BU = 10 and ASSET = 125, I have four rows, with BOOK = 'FED','CORP','AMT','LOCAL' and for BU = 20 and ASSET = 130, I have rows with BOOK = 'CORP','FED'. I want to identify BU/ASSET 20/130 as needing an 'AMT' row but to skip BU/ASSET 10/125 since it has an 'AMT' row. How do I accomplish this?

I meant to say Data Corruption has necessitated that we find the above scenario.