My database holds information gathered from sheep over several years. I have two large tables holding the relevant information. One I call the 'measured' data and one is 'visual' data. Basically both tables have animal ID as the first field. Each animal has a unique identifying number. In the measured table there is one record per animal so the ID column is a primary key. In the visual table however, several 'visual recordings' were done per animal so there may be between 1 and 4 records per ID. I do know that not every animal in the 'measured' table necessarily has some or any records in the 'visual' table but I am pretty sure that every animal ID that shows up in the 'visual' table DOES have a corresponding 'measured' record. (hope I haven't lost you yet). What I would like to do is create a table/ querie with 'measured ID' next to 'visual ID' to work out which animals are missing data. I have worked out so far how to get a total 'visual ID' tag list without duplicates but if I create a querie linking the visual with measured IDs it will only give me a list of those animals which have both. i would like a table with two columns and a eg blank in the 'visual ID' if the 'measured ID' doesn't match one so I can identify that particular animal. If you need further clarification I won't be surprised!