复制代码 代码如下:

create table td_base_data( id int(10) not null auto_increment,userId int(10) default '0',primary key (`id`))ENGINE=MyISAM DEFAULT CHARSET=gbk;
create table td_base_data_20090527( id int(10) not null auto_increment,userId int(10) default '0',primary key (`id`))ENGINE=MyISAM DEFAULT CHARSET=gbk;

insert into td_base_data(userId) values(1);
insert into td_base_data(userId) values(45);
insert into td_base_data(userId) values(45);
insert into td_base_data(userId) values(1);
insert into td_base_data(userId) values(45);
insert into td_base_data_20090527(userId) values(1);
insert into td_base_data_20090527(userId) values(45);
insert into td_base_data_20090527(userId) values(45);
insert into td_base_data_20090527(userId) values(1);
insert into td_base_data_20090527(userId) values(45);
insert into td_base_data_20090527(userId) values(45);

select count(userId) as cnumber from td_base_data where userId = '45';

select count(userId) as cnumber from td_base_data_20090527 where userId = '45';

select (select count(userId) from td_base_data where userId = '45') + (select count(userId) from td_base_data_20090527 where userId = '45') as cnumber;

select count(*) from
(
select id from td_base_data where userId = '45'
union
select id from td_base_data_20090527 where userId = '45'
) as tx;

select count(*) from
(
select * from td_base_data where userId = '45'
union
select * from td_base_data_20090527 where userId = '45'
) as tx;














select count(userId) as cnumber from
(
select userId from td_base_data where userId = '45'
union all
select userId from td_base_data_20090527 where userId = '45'
) as tx;