drop table if exists t1;
create table t1(a int primary key,b int);
insert into t1(a) values(1),(2),(3);
select * from t1 limit 0;
a	b
select * from t1 limit 1;
a	b
1	NULL
select * from t1 limit 3;
a	b
1	NULL
2	NULL
3	NULL
select * from t1 limit 4;
a	b
1	NULL
2	NULL
3	NULL
select /*+no_rewrite*/ * from (select * from t1 order by b limit 4) AS t2 limit 2;
a	b
1	NULL
2	NULL
select * from t1 limit -1;
ERROR 42000: You have an error in your SQL syntax; check the manual that corresponds to your OceanBase version for the right syntax to use near '-1' at line 1
drop table t1;
create table t1 (a int primary key,b int);
insert into t1(a) values (1),(2),(3),(4),(5),(6),(7);
select * FROM t1  ORDER BY a desc LIMIT 3;
a	b
7	NULL
6	NULL
5	NULL
select * FROM t1  ORDER BY a desc LIMIT 0;
a	b
select * FROM t1  ORDER BY a desc LIMIT 8;
a	b
7	NULL
6	NULL
5	NULL
4	NULL
3	NULL
2	NULL
1	NULL
select count(*) c FROM t1 WHERE a > 0 ORDER BY c LIMIT 3;
c
7
select sum(a) c FROM t1 WHERE a > 0 ORDER BY c LIMIT 3;
c
28
drop table t1;