合并来自两个不同数据库的相同SQL语句

Question

I have a mySQL SELECT statement that I run twice, once on each database. They perform the same action but I just need to change the database between the statements.

This is how it looks like:

   mysql_select_db("db1");
   mysql_query("SELECT results from table1 where date='2012-01-01'");
   mysql_select_db("db2");
   mysql_query("SELECT results from table1 where date='2012-01-01'");

Is there anyway to simplify this into one statement?

Answer 1

You can reference multiple databases in the same MySQL statement, and you can combine your two queries into a UNION :

SELECT results from db1.table1 where date='2012-01-01'
UNION ALL
SELECT results from db2.table1 where date='2012-01-01';