drop table if exists t1,t2,t3;
select count(*);
count(*)
1
select count(*) from dual;
count(*)
1
create table t1 (libname varchar(21), city varchar(256), primary key (libname));
select count(*) from t1;
count(*)
0
insert into t1 values ('test1','city1'),('test2','city2');
insert into t1 values ('l', null);
replace into t1 values ('2', null);
replace into t1 values ('test3','city3'),('test4','city4');
select count(*) from t1;
count(*)
6
select count(city) from t1;
count(city)
4
select count(t1.*) from t1;
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