79
79
t2 CREATE TEMPORARY TABLE `t2` (
82
82
UNIQUE KEY `a` (`a`,`b`),
85
85
insert into t2 select * from t1;
86
86
alter table t1 modify b blob not null, add c int not null, drop key a, add unique key (a,b(20),c), drop key b, add key (b(10));
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87
explain select * from t1 where a is null and b = 2;