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Oracle 视图view
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在我看来，oracle的视图就是用于将多个表的关联查询结果映射成【临时表】，视图与系统表中的数据是实时对应的。
我们可以像操作表的查询一样来操作视图查询。
视图写法：
CREATE OR REPLACE FORCE VIEW V_TEM
(
ID,
NAME
)
AS
SELECT ID,NAME FROM TABLE
项目中的一个案例，将一个自关联的结构表（行转多列）体现组织结构：市-区县-网格-乡镇-渠道
用到的知识点：
1、SYS_CONNECT_BY_PATH(字段,间隔符) 示例：SYS_CONNECT_BY_PATH(ID, '|')
2、SUBSTR()
3、INSTR()
备注：两函数SUBSTR()、INSTR()对待字符串的位置的索引是从1开始的（填写0和1都是代表从第1个位置开始）
sql代码：
DROP VIEW TLS.V_CHANNEL_PATH; CREATE OR REPLACE FORCE VIEW TLS.V_CHANNEL_PATH
(
ID,
PARENT_ID,
NAME,
ID_LEVEL,
TYPE,
IN_USE,
STATUS_TIME,
LEVEL_ID,
BANK_NAME,
ACCOUNT_NAME,
ACCOUNT_NO,
GROUP_ID,
CLASS,
CHANNEL_TEL,
QX_CHANNEL_ID,
PQ_CHANNEL_ID,
XZ_CHANNEL_ID,
QX_CHANNEL_NAME,
PQ_CHANNEL_NAME,
XZ_CHANNEL_NAME
)
AS
SELECT ID,
a.parent_id,
NAME,
id_level,
TYPE,
in_use,
status_time,
level_id,
bank_name,
account_name,
account_no,
GROUP_ID,
CLASS,
channel_tel,
SUBSTR (a.path_id,
INSTR (path_id,
'|',
1,
1)
+ 1,
INSTR (path_id,
'|',
1,
2)
- INSTR (path_id,
'|',
1,
1)
- 1)
qx_channel_id,
SUBSTR (a.path_id,
INSTR (path_id,
'|',
1,
2)
+ 1,
INSTR (path_id,
'|',
1,
3)
- INSTR (path_id,
'|',
1,
2)
- 1)
pq_channel_id,
SUBSTR (a.path_id,
INSTR (path_id,
'|',
1,
3)
+ 1,
INSTR (path_id,
'|',
1,
4)
- INSTR (path_id,
'|',
1,
3)
- 1)
xz_channel_id,
SUBSTR (a.path_name,
INSTR (path_name,
'|',
1,
1)
+ 1,
INSTR (path_name,
'|',
1,
2)
- INSTR (path_name,
'|',
1,
1)
- 1)
qx_channel_name,
SUBSTR (a.path_name,
INSTR (path_name,
'|',
1,
2)
+ 1,
INSTR (path_name,
'|',
1,
3)
- INSTR (path_name,
'|',
1,
2)
- 1)
pq_channel_name,
SUBSTR (a.path_name,
INSTR (path_name,
'|',
1,
3)
+ 1,
INSTR (path_name,
'|',
1,
4)
- INSTR (path_name,
'|',
1,
3)
- 1)
xz_channel_name
FROM ( SELECT a.*,
SUBSTR (SYS_CONNECT_BY_PATH (ID, '|'), 2) || '|' path_id,
SUBSTR (SYS_CONNECT_BY_PATH (NAME, '|'), 2) || '|'
path_name
FROM tl_channel a
START WITH ID = 1
CONNECT BY PRIOR ID = parent_id) a;
