oracle交集,并集,差集

[sql]

create table test1 

( 

 namevarchar(10), 

 NNvarchar(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 

( 

 namevarchar(10), 

 NNvarchar(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 * fromtest2; 

   

NAME      NN 

---------- ---------- 

test       A 

 

2、并集：union、unionall （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 rowsselected. 

[sql]

SQL> select* from test1 union allselect * fromtest2; 

   

NAME      NN 

---------- ---------- 

test       A 

test1      B 

test1      C 

test1      D 

test1      E 

test       A 

test2      B 

test2      C 

test2      D 

test2      E 

   

10 rowsselected. 

 

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hashjoin效率高呢?

[sql]

SQL> select* from test1 intersect select * fromtest2; 

   

   

Execution Plan 

---------------------------------------------------------- 

Plan hash value: 4290880088 

   

----------------------------------------------------------------------------- 

| Id  | Operation           |Name  | Rows | Bytes | Cost (%CPU)| Time    | 

----------------------------------------------------------------------------- 

|   0 | SELECTSTATEMENT    |       |     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 usedfor this statement (level=2) 

   

   

Statistics 

---------------------------------------------------------- 

          0  recursive calls 

          0  db block gets 

         14  consistent gets 

          0  physical reads 

          0  redosize 

        590  bytes sent via SQL*Netto client 

        523  bytes received via SQL*Netfrom client 

          2  SQL*Net roundtripsto/fromclient 

          2  sorts (memory) 

          0  sorts (disk) 

          1 rows processed 

   

   

SQL> selecta.* from test1 a,test2 b where a.name=b.nameand 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 (identifiedby operation id): 

--------------------------------------------------- 

   

   1 - access("A"."NAME"="B"."NAME"AND "A"."NN"="B"."NN") 

   

Note 

----- 

   -dynamic sampling usedfor this statement (level=2) 

   

   

Statistics 

---------------------------------------------------------- 

          0  recursive calls 

          0  db block gets 

         15  consistent gets 

          0  physical reads 

          0  redosize 

        590  bytes sent via SQL*Netto client 

        523  bytes received via SQL*Netfrom client 

          2  SQL*Net roundtripsto/fromclient 

          0  sorts (memory) 

          0  sorts (disk) 

          1 rows processed