There are 10 tables with similar structure but mutually exclusive records. A query needs to fetch some records from each of these tables. Which of the following is the best approach to do this?
Use UNION between the 10 SELECT statements
Execute separate SQL statements and let the front-end merge the results
Use UNION ALL between the 10 SELECT statements
Define a temporary table and populate it with data from the 10 SELECT statements and then do a single SELECT from this table