主键约束

最新推荐文章于 2024-07-25 17:46:08 发布

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最新推荐文章于 2024-07-25 17:46:08 发布 · 560 阅读

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#oracle

sys@ORCL> create table t (id int primary key,id1 int);

Table created.

sys@ORCL> select CONSTRAINT_NAME,COLUMN_NAME from  dba_cons_columns where table_name='T';

CONSTRAINT_NAME
------------------------------------------------------------
COLUMN_NAME
----------------------------------------------------------------------------------------------------
SYS_C0011647
ID


sys@ORCL> select index_name,column_name from dba_ind_columns where table_name='T';

INDEX_NAME
------------------------------------------------------------
COLUMN_NAME
----------------------------------------------------------------------------------------------------
SYS_C0011647
ID

默认创建约束和索引。

sys@ORCL>  alter table t modify (id int );

Table altered.

sys@ORCL> desc t
 Name                                                  Null?    Type
 ----------------------------------------------------- ------