SQL
UNION and UNION ALL
Stacking two result sets on top of each other. Learn the column compatibility rules, why UNION ALL is faster, and where ORDER BY belongs.
Set Operations
UNION, UNION ALL, INTERSECT, EXCEPT and column compatibility.
2 notes
Notes
SQL
INTERSECT, EXCEPT and Column Compatibility
The two set operations MySQL waited longest to add: rows in both sets, and rows in one set but not the other - plus how to emulate them where they are...