Answers:
它们确实使您在谷仓中四处奔跑,以使用GUI进行操作:
在开始之前,请确保您的列不违反唯一约束。
alter table location_key drop constraint pinky;
alter table your_table add constraint pinky unique(yourcolumn);
更改将立即生效:
Command(s) completed successfully.
这是通过GUI的另一种方法,即使它通过对象资源管理器中的索引(而不是约束),它也可以完全执行脚本的操作。
一件未明确介绍的事情是,Microsoft sql在后台为添加的约束创建了唯一索引
create table Customer ( id int primary key identity (1,1) , name nvarchar(128) )
--Commands completed successfully.
sp_help Customer
---> index
--index_name index_description index_keys
--PK__Customer__3213E83FCC4A1DFA clustered, unique, primary key located on PRIMARY id
---> constraint
--constraint_type constraint_name delete_action update_action status_enabled status_for_replication constraint_keys
--PRIMARY KEY (clustered) PK__Customer__3213E83FCC4A1DFA (n/a) (n/a) (n/a) (n/a) id
---- now adding the unique constraint
ALTER TABLE Customer ADD CONSTRAINT U_Name UNIQUE(Name)
-- Commands completed successfully.
sp_help Customer
---> index
---index_name index_description index_keys
---PK__Customer__3213E83FCC4A1DFA clustered, unique, primary key located on PRIMARY id
---U_Name nonclustered, unique, unique key located on PRIMARY name
---> constraint
---constraint_type constraint_name delete_action update_action status_enabled status_for_replication constraint_keys
---PRIMARY KEY (clustered) PK__Customer__3213E83FCC4A1DFA (n/a) (n/a) (n/a) (n/a) id
---UNIQUE (non-clustered) U_Name (n/a) (n/a) (n/a) (n/a) name
如您所见,这里有一个新的约束和一个新的索引U_Name