oracle中的交集、并集、差集
[sql]
create
table test1 (
name
varchar(10), NN
varchar(10)
);
insert
into test1 values(‘test‘,‘A‘);
insert
into test1 values(‘test1‘,‘B‘);
insert
into test1 values(‘test1‘,‘C‘);
insert
into test1 values(‘test1‘,‘D‘);
insert
into test1 values(‘test1‘,‘E‘);
create
table test2 (
name
varchar(10), NN
varchar(10)
);
insert
into test2 values(‘test‘,‘A‘);
insert
into test2 values(‘test2‘,‘B‘);
insert
into test2 values(‘test2‘,‘C‘);
insert
into test2 values(‘test2‘,‘D‘);
insert
into test2 values(‘test2‘,‘E‘);
1、交集：intersect[sql]
SQL>
select * from
test1 intersect
select * from
test2; NAME
NN ---------- ----------
test A
2、并集：union、union
all （注意两者的区别）[sql]
SQL>
select * from
test1 union
select * from
test2; NAME
NN ---------- ----------
test A
test1 B
test1 C
test1 D
test1 E
test2 B
test2 C
test2 D
test2 E
9
rows selected.
[sql]
SQL>
select * from
test1 union
all select *
from test2; NAME
NN ---------- ----------
test A
test1 B
test1 C
test1 D
test1 E
test A
test2 B
test2 C
test2 D
test2 E
10
rows selected.
3、差集：minus[sql]
SQL>
select * from
test1 minus select
* from
test2; NAME
NN ---------- ----------
test1 B
test1 C
test1 D
test1 E
SQL>
select * from
test2 minus select
* from
test1; NAME
NN ---------- ----------
test2 B
test2 C
test2 D
test2 E
最后对于求交集用intersect效率高呢还是hash
join效率高呢?[sql]
SQL>
select * from
test1 intersect
select * from
test2; Execution Plan
----------------------------------------------------------
Plan hash value: 4290880088
-----------------------------------------------------------------------------
| Id | Operation |
Name | Rows
| Bytes | Cost (%CPU)| Time
| -----------------------------------------------------------------------------
| 0 |
SELECT STATEMENT | | 5 | 140 | 8 (63)| 00:00:01 |
| 1 | INTERSECTION | | | | | |
| 2 | SORT
UNIQUE | | 5 | 70 | 4 (25)| 00:00:01 |
| 3 |
TABLE ACCESS
FULL| TEST1 | 5 | 70 | 3 (0)| 00:00:01 |
| 4 | SORT
UNIQUE | | 5 | 70 | 4 (25)| 00:00:01 |
| 5 |
TABLE ACCESS
FULL| TEST2 | 5 | 70 | 3 (0)| 00:00:01 |
-----------------------------------------------------------------------------
Note
-----
-
dynamic sampling used
for this statement (level=2)
Statistics ----------------------------------------------------------
0 recursive calls
0 db block gets
14 consistent gets
0 physical reads
0 redo
size 590 bytes sent via SQL*Net
to client
523 bytes received via SQL*Net
from client
2 SQL*Net roundtrips
to/from
client 2 sorts (memory)
0 sorts (disk)
1
rows processed
SQL>
select a.*
from test1 a,test2 b
where a.name=b.name
and a.nn=b.nn; Execution Plan
----------------------------------------------------------
Plan hash value: 497311279
----------------------------------------------------------------------------
| Id | Operation |
Name | Rows
| Bytes | Cost (%CPU)| Time
| ----------------------------------------------------------------------------
| 0 |
SELECT STATEMENT | | 5 | 140 | 7 (15)| 00:00:01 |
|* 1 | HASH
JOIN | | 5 | 140 | 7 (15)| 00:00:01 |
| 2 |
TABLE ACCESS
FULL| TEST1 | 5 | 70 | 3 (0)| 00:00:01 |
| 3 |
TABLE ACCESS
FULL| TEST2 | 5 | 70 | 3 (0)| 00:00:01 |
----------------------------------------------------------------------------
Predicate Information (identified
by operation id):
---------------------------------------------------
1 - access("A"."NAME"="B"."NAME"
AND "A"."NN"="B"."NN")
Note
-----
-
dynamic sampling used
for this statement (level=2)
Statistics ----------------------------------------------------------
0 recursive calls
0 db block gets
15 consistent gets
0 physical reads
0 redo
size 590 bytes sent via SQL*Net
to client
523 bytes received via SQL*Net
from client
2 SQL*Net roundtrips
to/from
client 0 sorts (memory)
0 sorts (disk)
1
rows processed原文地址：http://blog.csdn.net/lhl6688/article/details/45094369
