alter table

最新推荐文章于 2025-02-18 19:14:22 发布

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#table #constraints

假设 alter table table_name 语句都是相同的，下面只列出之后的语句。

如 alter table t_name add (test varchar2(20)); 只列出 add (test varcahr2(20);

--增加 add

add coulmn_name datatype column_properties;

add column_constraint; -- constraint con_name primary key col_name

-- constraint con_name foreign key(col_name) references table_name(col_name)

--修改 modify

modify column_name datatype default d_value column_constraint;

-- 删除 drop

drop column column_name [cascade constraints];

drop checkpoint ck_integer;

drop constraint_name;

--改名 rename

rename column old_name to new_name;

rename constraint old_name to new_name;

--约束

{ ADD { out_of_line_constraint
        [ out_of_line_constraint ]...
      | out_of_line_REF_constraint
      }
| MODIFY { CONSTRAINT constraint
         | PRIMARY KEY
         | UNIQUE (column [, column ]...)
         }
         constraint_state
| RENAME CONSTRAINT old_name TO new_name
| drop_constraint_clause
}

--删除约束

DROP
   { { PRIMARY KEY
     | UNIQUE (column [, column ]...)
     }
     [ CASCADE ]
     [ { KEEP | DROP } INDEX ]
   | CONSTRAINT constraint
     [ CASCADE ]
   }