t1,t2表连接的结果的行数不会超过两个表的最大行数的表的行数？？
很拗口，
简单的说：
t1表m行
t2表n行
m>n
做两个表的联合查询,其结果集行数= to_date('2015-05-16', 'yyyy-mm-dd')
and a.scan_time = to_date('2015-05-16', 'yyyy-mm-dd')
and s.scan_time = to_date('2015-05-16', 'yyyy-mm-dd')
and a.scan_time = to_date('2015-05-16', 'yyyy-mm-dd')
and s.scan_time
SQL> select * from t;
ID NAME
---------- ----------
1 2++
2 2
1 c++
1 c++
1 c++
1 c++
6 rows selected.
SQL> select * from t2;
ID NAME
---------- ----------
1 c++
1 c++
1 c++
1 c++
1 c++
1 c++
1 c++
1 c++
8 rows selected.
SQL> select count(*) from t ,t2 where t.id = t2.id;
COUNT(*)
----------
40
SQL>
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