003 数据库学习笔记--创建约束

--------------------------------创建表结构时创建约束--------------------------------

主键约束：

　　Id int identity(1,1) primary key not null

外键约束：

　　TypeId int not null foreign key references 主表(主键列)

Unique唯一约束：

　　DeviceNo varchar(50) unique not null

Default默认约束：

　　DeviceName varchar(100) default 'CT'

Check约束：

　　Price decimal(18,2) check(0<Price<10000) default(0) not null

--------------------------------创建表结构之后创建约束--------------------------------

主键：alter table 表名 add constraint pk_constraintname primary key(主键列)

外键：alter table 表名 add constraint fk_constraintname foreign key(从表列) references 主表(主表列)

Unique：alter table 表名 add constraint uk_constraintname unique(列名，列名)——可单例或多列

Check：alter table 表名 add constraint ck_constraintname check(0<Price<10000) ——check(逻辑表达式)

Default：alter table 表名 add constraint df_constraintname default(0) for Price

ALTER TABLE UserRIQC ALTER COLUMN id nvarchar(50) NOT NULL;
if object_id(N'pk_id','PK') is null
ALTER TABLE TableMutualRecognition ADD CONSTRAINT pk_id PRIMARY KEY (id);
if object_id(N'pk_reportid','PK') is null
ALTER TABLE TableMutualRecognitionReport ADD CONSTRAINT pk_reportid PRIMARY KEY (id);
if object_id(N'pk_userid','PK') is null
ALTER TABLE UserRIQC ADD CONSTRAINT pk_userid PRIMARY KEY (id);
if object_id(N'pk_logid','PK') is null
ALTER TABLE AuditLog ADD CONSTRAINT pk_logid PRIMARY KEY (id);
if object_id(N'pk_expertgroupid','PK') is null
ALTER TABLE DictExpertGroup ADD CONSTRAINT pk_expertgroupid PRIMARY KEY (id);
if object_id(N'pk_qualityitemsid','PK') is null
ALTER TABLE DictQualityItems ADD CONSTRAINT pk_qualityitemsid PRIMARY KEY (QualityItemsNo);
if object_id(N'pk_reviewitemsid','PK') is null
ALTER TABLE DictReviewItems ADD CONSTRAINT pk_reviewitemsid PRIMARY KEY (ReviewItemsNo);
if object_id(N'pk_tbimgqaitemsid','PK') is null
ALTER TABLE TableImageQualityItems ADD CONSTRAINT pk_tbimgqaitemsid PRIMARY KEY (QualityDescriptionNo);
if object_id(N'pk_loginlogid','PK') is null
ALTER TABLE LoginLog ADD CONSTRAINT pk_loginlogid PRIMARY KEY (id);