问题描述

我为在 Oracle SQL 中创建的多个表的每个约束定义了一个名称.

I have defined a name for each of the constraint for the multiple tables that I have created in Oracle SQL.

问题是要删除特定表的列的约束，我需要知道我为每个约束提供的名称，但我已经忘记了.

The problem is that to drop a constraint for the column of a particular table I need to know the name that I have supplied for each constraints, which I have forgotten.

如何列出我为表的每一列指定的所有约束名称?

How do I list out all the names of constraints that I have specified for each column of a table?

是否有任何 SQL 语句可以执行此操作?

Is there any SQL statement for doing so?

推荐答案

需要查询数据字典，特别是USER_CONS_COLUMNS视图查看表列和对应的约束:

You need to query the data dictionary, specifically the USER_CONS_COLUMNS view to see the table columns and corresponding constraints:

SELECT *
  FROM user_cons_columns
 WHERE table_name = '<your table name>';

仅供参考，除非您专门使用小写名称(使用双引号)创建了表格，否则表格名称将默认为大写，因此请确保在您的查询中也是如此.

FYI, unless you specifically created your table with a lower case name (using double quotes) then the table name will be defaulted to upper case so ensure it is so in your query.

如果您希望查看有关约束本身的更多信息，请查询 USER_CONSTRAINTS 视图:

If you then wish to see more information about the constraint itself query the USER_CONSTRAINTS view:

SELECT *
  FROM user_constraints
 WHERE table_name = '<your table name>'
   AND constraint_name = '<your constraint name>';

如果表保存在不是默认架构的架构中，那么您可能需要将视图替换为:

If the table is held in a schema that is not your default schema then you might need to replace the views with:

all_cons_columns

和

all_constraints

添加到 where 子句:

adding to the where clause:

   AND owner = '<schema owner of the table>'

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