select * from t3 where c3='2';
select * from t3 where c3>'2';
select * from t3 where c3<'2';
select * from t3 where c3>='2';
select * from t3 where c3<='2';
select * from t3 where c3!='2';
select * from t3 where c3<=>'2';
select * from t3 where c3 is null;
select * from t3 where c3 is false;
select * from t3 where c3 is true;
select * from t3 where c3+'2'>'1';
select * from t3 where c3-'2'>'1';
select * from t3 where c3*'2'>'1';
select * from t3 where c3/'2'>'1';
select * from t3 where length(concat(c3, '2'))>'1';