在Oracle中，“OR扩展”可以有查询转换吗？
♣ 答案部分
同一字段：
1LHR@orclasm > SELECT * FROM SCOTT.EMP A WHERE A.EMPNO =7369 OR A.EMPNO=1;
2
3 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
4---------- ---------- --------- ---------- ------------------- ---------- ---------- ----------
5 7369 SMITH CLERK 7902 1980-12-17 00:00:00 800 20
6
7
8Execution Plan
9----------------------------------------------------------
10Plan hash value: 2355049923
11
12---------------------------------------------------------------------------------------
13| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
14---------------------------------------------------------------------------------------
15| 0 | SELECT STATEMENT | | 1 | 87 | 2 (0)| 00:00:01 |
16| 1 | INLIST ITERATOR | | | | | |
17| 2 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 87 | 2 (0)| 00:00:01 |
18|* 3 | INDEX UNIQUE SCAN | PK_EMP | 1 | | 3 (0)| 00:00:01 |
19---------------------------------------------------------------------------------------
20
21Predicate Information (identified by operation id):
22---------------------------------------------------
23
24 3 - access("A"."EMPNO"=1 OR "A"."EMPNO"=7369)
25
26Note
27-----
28 - dynamic sampling used for this statement (level=2)
29
30
31Statistics
32----------------------------------------------------------
33 23 recursive calls
34 5 db block gets
35 3 consistent gets
36 0 physical reads
37 1628 redo size
38 1025 bytes sent via SQL*Net to client
39 520 bytes received via SQL*Net from client
40 2 SQL*Net roundtrips to/from client
41 0 sorts (memory)
42 0 sorts (disk)
43 1 rows processed
44
45LHR@orclasm > SELECT /*+OR_EXPAND(A EMPNO)*/ * FROM SCOTT.EMP A WHERE A.EMPNO =7369 OR A.EMPNO=1;
46
47 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
48---------- ---------- --------- ---------- ------------------- ---------- ---------- ----------
49 7369 SMITH CLERK 7902 1980-12-17 00:00:00 800 20
50
51
52Execution Plan
53----------------------------------------------------------
54Plan hash value: 2259546459
55
56---------------------------------------------------------------------------------------
57| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
58---------------------------------------------------------------------------------------
59| 0 | SELECT STATEMENT | | 2 | 174 | 2 (0)| 00:00:01 |
60| 1 | CONCATENATION | | | | | |
61| 2 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 87 | 1 (0)| 00:00:01 |
62|* 3 | INDEX UNIQUE SCAN | PK_EMP | 1 | | 1 (0)| 00:00:01 |
63| 4 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 87 | 1 (0)| 00:00:01 |
64|* 5 | INDEX UNIQUE SCAN | PK_EMP | 1 | | 1 (0)| 00:00:01 |
65---------------------------------------------------------------------------------------
66
67Predicate Information (identified by operation id):
68---------------------------------------------------
69
70 3 - access("A"."EMPNO"=1)
71 5 - access("A"."EMPNO"=7369)
72
73Note
74-----
75 - dynamic sampling used for this statement (level=2)
76
77
78Statistics
79----------------------------------------------------------
80 23 recursive calls
81 4 db block gets
82 3 consistent gets
83 0 physical reads
84 1560 redo size
85 1021 bytes sent via SQL*Net to client
86 520 bytes received via SQL*Net from client
87 2 SQL*Net roundtrips to/from client
88 0 sorts (memory)
89 0 sorts (disk)
90 1 rows processed
91
92LHR@orclasm >
不同字段：
1LHR@orclasm > SELECT * FROM SCOTT.EMP A WHERE A.EMPNO =7369 OR A.ENAME='DBA';
2
3 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
4---------- ---------- --------- ---------- ------------------- ---------- ---------- ----------
5 7369 SMITH CLERK 7902 1980-12-17 00:00:00 800 20
6
7
8Execution Plan
9----------------------------------------------------------
10Plan hash value: 3956160932
11
12--------------------------------------------------------------------------
13| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
14--------------------------------------------------------------------------
15| 0 | SELECT STATEMENT | | 1 | 87 | 3 (0)| 00:00:01 |
16|* 1 | TABLE ACCESS FULL| EMP | 1 | 87 | 3 (0)| 00:00:01 |
17--------------------------------------------------------------------------
18
19Predicate Information (identified by operation id):
20---------------------------------------------------
21
22 1 - filter("A"."EMPNO"=7369 OR "A"."ENAME"='DBA')
23
24Note
25-----
26 - dynamic sampling used for this statement (level=2)
27
28
29Statistics
30----------------------------------------------------------
31 28 recursive calls
32 4 db block gets
33 16 consistent gets
34 0 physical reads
35 1544 redo size
36 1021 bytes sent via SQL*Net to client
37 520 bytes received via SQL*Net from client
38 2 SQL*Net roundtrips to/from client
39 0 sorts (memory)
40 0 sorts (disk)
41 1 rows processed
42
43LHR@orclasm > SELECT /*+OR_EXPAND(A EMPNO)*/ * FROM SCOTT.EMP A WHERE A.EMPNO =7369 OR A.ENAME='DBA';
44
45 EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
46---------- ---------- --------- ---------- ------------------- ---------- ---------- ----------
47 7369 SMITH CLERK 7902 1980-12-17 00:00:00 800 20
48
49
50Execution Plan
51----------------------------------------------------------
52Plan hash value: 2453891490
53
54---------------------------------------------------------------------------------------
55| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
56---------------------------------------------------------------------------------------
57| 0 | SELECT STATEMENT | | 2 | 174 | 3 (0)| 00:00:01 |
58| 1 | CONCATENATION | | | | | |
59|* 2 | TABLE ACCESS FULL | EMP | 1 | 87 | 2 (0)| 00:00:01 |
60|* 3 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 87 | 1 (0)| 00:00:01 |
61|* 4 | INDEX UNIQUE SCAN | PK_EMP | 1 | | 1 (0)| 00:00:01 |
62---------------------------------------------------------------------------------------
63
64Predicate Information (identified by operation id):
65---------------------------------------------------
66
67 2 - filter("A"."ENAME"='DBA')
68 3 - filter(LNNVL("A"."ENAME"='DBA'))
69 4 - access("A"."EMPNO"=7369)
70
71Note
72-----
73 - dynamic sampling used for this statement (level=2)
74
75
76Statistics
77----------------------------------------------------------
78 31 recursive calls
79 4 db block gets
80 25 consistent gets
81 0 physical reads
82 1560 redo size
83 1021 bytes sent via SQL*Net to client
84 520 bytes received via SQL*Net from client
85 2 SQL*Net roundtrips to/from client
86 0 sorts (memory)
87 0 sorts (disk)
88 1 rows processed
本文选自《Oracle程序员面试笔试宝典》，作者：李华荣。
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