如何在Oracle中查找具有表外键的表？

Question

我打算从一个表中删除数据，我想知道在 Oracle 中有多少表以及哪些表具有对这个特定表的外键引用。因为我必须将外键设置为空。我想知道对这个特定表有 FK 的所有表的列表。

Answer 1

SELECT
  FK.OWNER||'.'||FK.TABLE_NAME AS CHILD_TABLE,
  SRC.OWNER||'.'||SRC.TABLE_NAME AS PARENT_TABLE,
  FK.CONSTRAINT_NAME AS FK_CONSTRAINT,
  SRC.CONSTRAINT_NAME AS REFERENCED_CONSTRAINT
FROM ALL_CONSTRAINTS FK
JOIN ALL_CONSTRAINTS SRC ON FK.R_CONSTRAINT_NAME = SRC.CONSTRAINT_NAME
WHERE
  FK.CONSTRAINT_TYPE = 'R'
  AND SRC.OWNER = 'MY_SCHEMA'
  AND SRC.TABLE_NAME = 'MY_TABLE';

我有一种情况，我感兴趣的表不属于我连接的架构。所以我需要修改currently accepted answer 中的查询以使用ALL_CONSTRAINTS 而不是USER_CONSTRAINTS。在这个过程中，我犯了一个错误，我发现接受的答案很难阅读，所以我可以修复它。 （缺乏解释并没有帮助。）结果，我最终提出了自己的查询。基本是一样的，不过我觉得摸起来容易一点。

FK.CONSTRAINT_TYPE = 'R' 将FK 过滤到一组外键约束，并且连接将这些外键与其“引用约束”配对。 （引用的约束通常是“父”表的主键。）最后，我们使用SRC.OWNER = 'MY_SCHEMA' AND SRC.TABLE_NAME = 'MY_TABLE' 过滤到我们感兴趣的父表。

当然，如果您愿意，您可以将其切换为使用USER_CONSTRAINTS；只需删除SRC.OWNER 检查和SELECT 中的OWNER 前缀即可。

Answer 2

SELECT d.table_name,

       d.constraint_name "Primary Constraint Name",

       b.constraint_name "Referenced Constraint Name"

FROM user_constraints d,

     (SELECT c.constraint_name,

             c.r_constraint_name,

             c.table_name

      FROM user_constraints c 

      WHERE table_name='EMPLOYEES' --your table name instead of EMPLOYEES

      AND constraint_type='R') b

WHERE d.constraint_name=b.r_constraint_name

Answer 3

以下查询将给出在 TABLE_NAME 上定义的所有外键约束：

select baseTable.* from all_constraints baseTable , all_constraints referentedTable 
    where baseTable.R_CONSTRAINT_NAME = referentedTable.CONSTRAINT_NAME
    and baseTable.constraint_type = 'R'
    and referentedTable.table_name = 'TABLE_NAME';

Answer 4

也许我误解了 Walker 的要求，但我的理解是：如何找到具有对特定表的外键引用的表（例如：EMPLOYEES）。

如果我尝试 Kupa 的回答：

select d.table_name,
       d.constraint_name "Primary Constraint Name",
       b.constraint_name "Referenced Constraint Name"

from user_constraints d,

     (select c.constraint_name,
             c.r_constraint_name,
             c.table_name
      from user_constraints c 
      where table_name='EMPLOYEES' --your table name instead of EMPLOYEES
      and constraint_type='R') b

where d.constraint_name=b.r_constraint_name

我得到了 EMPLOYEES 有外键引用的表。

EMPLOYEES.foreign_key => TABLES.primary_key

---

请参阅下面更新的 sql 以检索具有对 EMPLOYEES 的外键引用的表。

TABLES.foreign_key => EMPLOYEES.primary_key

select b.table_name "Table Name",
   b.constraint_name "Constraint Name",
   d.table_name "Referenced Table Name",
   d.constraint_name "Referenced Constraint Name"

from user_constraints d,

 (select c.constraint_name,
         c.r_constraint_name,
         c.table_name
  from user_constraints c
  where constraint_type='R') b

where d.table_name = 'EMPLOYEES' --your table name instead of EMPLOYEES
and b.r_constraint_name = d.constraint_name;

Answer 5

如果您还需要包含这些字段：

select b.table_name      "Referencing Table", 
       b.CONSTRAINT_NAME "Referencing Constraint",
       (select wm_concat(column_name)
          from all_cons_columns
         where owner = b.owner
           and constraint_name = b.CONSTRAINT_NAME
       ) "Referencing Columns",
       a.CONSTRAINT_NAME         "Referenced Constraint",
       (select wm_concat(column_name)
          from all_cons_columns
         where owner = a.owner
           and constraint_name = a.CONSTRAINT_NAME
       ) "Referenced columns"
  from all_constraints a,
       all_constraints b
 where a.owner = b.r_owner
   and a.owner = '<<OWNER>>'
   and a.table_name = '<<TABLE_NAME>>'
   and a.constraint_type in ('P', 'U')
   and b.constraint_type = 'R'
   and b.R_CONSTRAINT_NAME = a.constraint_name

Answer 6

无需手动执行此步骤 - 您只需使用 cascading delete。

Answer 7

SELECT a.table_name, a.column_name, a.constraint_name, c.owner, 
       -- referenced pk
       c.r_owner, c_pk.table_name r_table_name, c_pk.constraint_name r_pk
  FROM all_cons_columns a
  JOIN all_constraints c ON a.owner = c.owner
                        AND a.constraint_name = c.constraint_name
  JOIN all_constraints c_pk ON c.r_owner = c_pk.owner
                           AND c.r_constraint_name = c_pk.constraint_name
 WHERE c.constraint_type = 'R'
   AND a.table_name = :TableName

Answer 8

SELECT CONSTRAINT_NAME from ALL_CONSTRAINTS WHERE OWNER= sys_context('userenv','current_schema') AND CONSTRAINT_TYPE='R';