作者:温济鸿_345 | 来源:互联网 | 2014-07-11 17:33
oracle集合union、unionall、intersect、minusoracle中集合的效率比普通的比较要高测试案例--测试表数据www.2cto.comSQL>selectstuidfromzr_stu;STUID-----------12...SyntaxHig
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
www.2cto.com
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
www.2cto.com
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
www.2cto.com
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
www.2cto.com
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
www.2cto.com
--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