oracle聚合union、union all、intersect、minus
日期：2014-05-16 浏览次数：20458 次
oracle集合union、union all、intersect、minus
oracle中集合的效率比普通的比较要高
测试案例
--测试表数据
SQL> select stuid from zr_stu;
STUID
-----------
1
2
3
4
5
6
7
7 rows selected
Executed in 0.14 seconds
--表数据
SQL> select stuid from zr_stu where stuid > 3;
STUID
-----------
4
5
6
7
Executed in 0.047 seconds
SQL> select stuid from zr_stu where stuid < 6;
STUID
-----------
1
2
3
4
5
Executed in 0.109 seconds
--union
SQL> select stuid from zr_stu where stuid > 4 union select stuid from zr_stu where stuid < 6;
STUID
----------
1
2
3
4
5
6
7
7 rows selected
Executed in 0.031 seconds
--union all
SQL> select stuid from zr_stu where stuid > 4
2 union all
3 select stuid from zr_stu where stuid < 6;
STUID
----------
5
6
7
1
2
3
4
5
8 rows selected
Executed in 0.156 seconds
--intersect
SQL> select stuid from zr_stu where stuid > 4
2 intersect
3 select stuid from zr_stu where stuid < 6;
STUID
----------
5
Executed in 0.078 seconds
--minus
SQL> select stuid from zr_stu where stuid > 4
2 minus
3 select stuid from zr_stu where stuid < 6;
STUID
----------
6
7
Executed in 0.062 seconds
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