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drop table if exists t1;
create table t1 (t1 char(3) primary key);
insert into t1 values("ABC");
insert into t1 values("ABA");
insert into t1 values("AB%");
select * from t1 where t1="ABC";
t1
ABC
select * from t1 where t1="ABCD";
t1
select * from t1 where t1 like "a_\%";
t1
AB%
describe select * from t1 where t1="ABC";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 const PRIMARY PRIMARY 3 const 1 Using index
describe select * from t1 where t1="ABCD";
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables
drop table t1;
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