我有一个非常大的Oracle数据库,有许多表和数百万行。我需要删除其中一个,但是要确保删除它不会破坏任何指向它作为外键记录的其他依赖行。有没有办法获得指向此行的所有其他记录或至少表格模式的列表?我知道我可以尝试自己删除它,并捕获异常,但我不会自己运行脚本,需要它第一次运行清理。
我有来自Oracle的SQL Developer工具和来自AllRoundAutomations的PL / SQL Developer。
提前致谢!
我总是看着起始桌上的外键,然后回去工作。数据库工具通常具有依赖项或约束节点。我知道PL / SQL Developer有办法看到FK,但是我用了它已经有一段时间了,所以我无法解释它......
只需用表名替换XXXXXXXXXXXX ......
/* The following query lists all relationships */
select
a.owner||'.'||a.table_name "Referenced Table"
,b.owner||'.'||b.table_name "Referenced by"
,b.constraint_name "Foreign Key"
from all_constraints a, all_constraints b
where
b.constraint_type = 'R'
and a.constraint_name = b.r_constraint_name
and b.table_name='XXXXXXXXXXXX' -- Table name
order by a.owner||'.'||a.table_name
这是我列出对表的所有引用的解决方案:
select
src_cc.owner as src_owner,
src_cc.table_name as src_table,
src_cc.column_name as src_column,
dest_cc.owner as dest_owner,
dest_cc.table_name as dest_table,
dest_cc.column_name as dest_column,
c.constraint_name
from
all_constraints c
inner join all_cons_columns dest_cc on
c.r_constraint_name = dest_cc.constraint_name
and c.r_owner = dest_cc.owner
inner join all_cons_columns src_cc on
c.constraint_name = src_cc.constraint_name
and c.owner = src_cc.owner
where
c.constraint_type = 'R'
and dest_cc.owner = 'MY_TARGET_SCHEMA'
and dest_cc.table_name = 'MY_TARGET_TABLE'
--and dest_cc.column_name = 'MY_OPTIONNAL_TARGET_COLUMN'
;
使用此解决方案,您还可以获得哪个表的哪一列引用目标表的哪一列(并且可以对其进行过滤)的信息。
我最近遇到了类似的问题,但很快就遇到了,找到直接的依赖关系是不够的。所以我写了一个查询来显示多级外键依赖关系的树:
SELECT LPAD(' ',4*(LEVEL-1)) || table1 || ' <-- ' || table2 tables, table2_fkey
FROM
(SELECT a.table_name table1, b.table_name table2, b.constraint_name table2_fkey
FROM user_constraints a, user_constraints b
WHERE a.constraint_type IN('P', 'U')
AND b.constraint_type = 'R'
AND a.constraint_name = b.r_constraint_name
AND a.table_name != b.table_name
AND b.table_name <> 'MYTABLE')
CONNECT BY PRIOR table2 = table1 AND LEVEL <= 5
START WITH table1 = 'MYTABLE';
在我的数据库中使用SHIPMENT作为MYTABLE时,它给出了这样的结果:
SHIPMENT <-- ADDRESS
SHIPMENT <-- PACKING_LIST
PACKING_LIST <-- PACKING_LIST_DETAILS
PACKING_LIST <-- PACKING_UNIT
PACKING_UNIT <-- PACKING_LIST_ITEM
PACKING_LIST <-- PO_PACKING_LIST
...
我们可以使用数据字典来标识引用相关表的主键的表。从那里我们可以生成一些动态SQL来查询这些表以获取我们想要的值:
SQL> declare
2 n pls_integer;
3 tot pls_integer := 0;
4 begin
5 for lrec in ( select table_name from user_constraints
6 where r_constraint_name = 'T23_PK' )
7 loop
8 execute immediate 'select count(*) from '||lrec.table_name
9 ||' where col2 = :1' into n using &&target_val;
10 if n = 0 then
11 dbms_output.put_line('No impact on '||lrec.table_name);
12 else
13 dbms_output.put_line('Uh oh! '||lrec.table_name||' has '||n||' hits!');
14 end if;
15 tot := tot + n;
16 end loop;
17 if tot = 0
18 then
19 delete from t23 where col2 = &&target_val;
20 dbms_output.put_line('row deleted!');
21 else
22 dbms_output.put_line('delete aborted!');
23 end if;
24 end;
25 /
Enter value for target_val: 6
No impact on T34
Uh oh! T42 has 2 hits!
No impact on T69
delete aborted!
PL/SQL procedure successfully completed.
SQL>
这个例子有点欺骗。目标主键的名称是硬编码的,并且引用列在所有从属表上具有相同的名称。修复这些问题留给读者练习;)
我很惊讶基于外键关系找到表的依赖顺序是多么困难。我需要它,因为我想从所有表中删除数据并再次导入。这是我写的用于按依赖顺序列出表的查询。我能够使用下面的查询编写删除脚本,并以相反的顺序使用查询结果再次导入。
SELECT referenced_table
,MAX(lvl) for_deleting
,MIN(lvl) for_inserting
FROM
( -- Hierarchy of dependencies
SELECT LEVEL lvl
,t.table_name referenced_table
,b.table_name referenced_by
FROM user_constraints A
JOIN user_constraints b
ON A.constraint_name = b.r_constraint_name
and b.constraint_type = 'R'
RIGHT JOIN user_tables t
ON t.table_name = A.table_name
START WITH b.table_name IS NULL
CONNECT BY b.table_name = PRIOR t.table_name
)
GROUP BY referenced_table
ORDER BY for_deleting, for_inserting;
Oracle约束使用表索引来引用数据。 要找出哪些表引用一个表,只需按相反的顺序查找索引。
/* Toggle ENABLED and DISABLE status for any referencing constraint: */
select 'ALTER TABLE '||b.owner||'.'||b.table_name||' '||
decode(b.status, 'ENABLED', 'DISABLE ', 'ENABLE ')||
'CONSTRAINT '||b.constraint_name||';'
from all_indexes a,
all_constraints b
where a.table_name='XXXXXXXXXXXX' -- Table name
and a.index_name = b.r_constraint_name;
Obs。:禁用引用可以显着改善DML命令(更新,删除和插入)的时间。
这可以在批量操作中提供很多帮助,您知道所有数据都是一致的。
/* List which columns are referenced in each constraint */
select ' TABLE "'||b.owner||'.'||b.table_name||'"'||
'('||listagg (c.column_name, ',') within group (order by c.column_name)||')'||
' FK "'||b.constraint_name||'" -> '||a.table_name||
' INDEX "'||a.index_name||'"'
"REFERENCES"
from all_indexes a,
all_constraints b,
all_cons_columns c
where rtrim(a.table_name) like 'XXXXXXXXXXXX' -- Table name
and a.index_name = b.r_constraint_name
and c.constraint_name = b.constraint_name
group by b.owner, b.table_name, b.constraint_name, a.table_name, a.index_name
order by 1;