Here is an interesting challenge that I ran into in the Data Warehouse environment. While debugging a particular business user query, I joined between a string built in a sub-query to a column in a particular fact table with some 20million rows. BTW, I was using MySQL 5.0 and Toad 4.5 to run this query and instead of getting any result I got the following error!
The query was simple and similar to
MySQL Database Error: Illegal mix of collations (utf8_general_ci,COERCIBLE) and (latin1_swedish_ci,IMPLICIT) for operation '=' 22 0
The query was simple and similar to
SELECT s.str, s.d1, s.d2
FROM (
SELECT distinct 'string' str, dimension1 d1, dimension 2 d2
FROM table_1
WHERE ...
) s
LEFT OUTER JOIN table_2 t2
ON ...
WHERE s.str = t2.str
AND ...
