CASE [t1.field1 ]
WHEN значение1 THEN DELETE t1 where t1.field1 = "значение1"
WHEN значение2 THEN UPDATE t2.field2 = t1.field2 and t2.field3 = t1.field3 where t2.id = t1.id
WHEN значение3 THEN UPDATE t2.field2 = кастомное значение где t2.id = t1.id
END