drop table if exists t;
create table t (id int, c1 timestamp);
show columns from t;
explain t;
describe t;
desc t;
desc t c1;
desc t id;

drop table if exists t;
create table t(id int primary key, a int, b int);
set session tidb_hashagg_partial_concurrency = 1;
set session tidb_hashagg_final_concurrency = 1;
explain select group_concat(a) from t group by id;
explain select group_concat(a, b) from t group by id;
drop table t;
