Hi, I am seeking to compare two spreadsheets created by the City of Los Angeles that identify all the billboards in the city from 2011 and from 2014. The 2011 inventory contains 9000 signs (each with its own row in the spreadsheet) with about 40 columns of data for each row. In 2014, the city released much less data for each sign (only about 15 columns of data for each row), and identified many fewer signs (only about 8500 signs/rows).

First, I would like to identify those signs/rows that exist in the 2011 spreadsheet but are missing from the 2014 spreadsheet.

Second, for the 8500 signs in the 2014 spreadsheet, I would like to append the extra 25 columns of data that exist for each sign in the 2011 spreadsheet.

Each sign contains a case number, which is listed in the "case number" column. However, many signs share a case number with one other sign (one billboard pole can contain two signs); in these cases, the "sign face" column distinguishes between two signs on one billboard with an "A" for one and a "B" for the other. So between the case number and the sign face columns, each sign should be able to be uniquely identified.

Any ideas are greatly appreciated! Thanks!