My source data is a set of annual tables that have been merged into one.
If I use these definition queries, only the first one works. Is there an error in my SQL statement?
For one, make sure the date field is indexed or you will be suffering some terrible performance with data from the layer.
When working with ranges in file geodatabases, whether dates or numbers in general, BETWEEN performs better. What happens if you try:
Status = 'Completed' AND (Delivery_Date BETWEEN date '2017-01-15 00:00:00' AND date '2018-01-15 00:00:00')