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In an effort to speed up my database updates, I've been looking for ways to batch some of my updates. CASE seems like the way to go: mysql> create table bar(a tinyint, b tinyint); Query OK, 0 rows affected (0.02 sec) mysql> insert into bar(a) values(1), (2), (3), (4), (5); Query OK, 5 rows affected (0.00 sec) Records: 5 Duplicates: 0 Warnings: 0 mysql> select * from bar; +------+------+ | a | b | +------+------+ | 1 | NULL | | 2 | NULL | | 3 | NULL | | 4 | NULL | | 5 | NULL | +------+------+ 5 rows in set (0.00 sec) mysql> update bar set b = case a -> when 1 then 42 -> when 2 then 43 -> when 3 then 44 -> else 45 -> end; Query OK, 5 rows affected (0.00 sec) Rows matched: 5 Changed: 5 Warnings: 0 mysql> select * from bar; +------+------+ | a | b | +------+------+ | 1 | 42 | | 2 | 43 | | 3 | 44 | | 4 | 45 | | 5 | 45 | +------+------+ 5 rows in set (0.00 sec) I see stuff online which warns not…