How to verify if two tables have exactly the same data?
If you do not care about one table being less than the other, but you only care about differences in the attributes:
SELECT * FROM Table1
UNION
SELECT * FROM Table2
If you get records greater than the max number of the two tables, they don't have same data.
You can just use CHECKSUM TABLE and compare the results. You can even alter the table to enable live checksums so that they are continuously available.
CHECKSUM TABLE original_table, backup_table;
It doesn't require the tables to have a primary key.
I would write three queries.
An inner join to pick up the rows where the primary key exists in both tables, but there is a difference in the value of one or more of the other columns. This would pick up changed rows in original.
A left outer join to pick up the rows that are in the original tables, but not in the backup table (i.e. a row in original has a primary key that does not exist in backup). This would return rows inserted into the original.
A right outer join to pick up the rows in backup which no longer exist in the original. This would return rows that have been deleted from the original.
You could union the three queries together to return a single result set. If you did this you would need to add a column to indicate what type of row it is (updated, inserted or deleted).
With a bit of effort, you might be able to do this in one query using a full outer join. Be careful with outer joins, as they behave differently in different SQL engines. Predicates put in the where clause, instead of the join clause can sometimes turn your outer join into an inner join.