Note:As with other constraints, naming aFOREIGN KEYconstraint usingCONSTRAINT constraint_nameis optional. But doing so makes it easier to make changes to or delete the constraint. This is especially helpful when defining multiple constraints. Recommended Readings:...
To allow naming of aFOREIGN KEYconstraint, and for defining aFOREIGN KEYconstraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: CREATETABLEOrders ( OrderID intNOTNULL, OrderNumber intNOTNULL, ...
To allow naming of a FOREIGN KEY constraint, and for defining a FOREIGN KEY constraint on multiple columns, use the following SQL syntax:MySQL / SQL Server / Oracle / MS Access:CREATE TABLE Orders ( O_Id int NOT NULL, OrderNo int NOT NULL, P_Id int, PRIMARY KEY (O_Id), CONSTRAINT...
ERROR: foreign key constraint "constraint_name" violation：试图在父表中没有对应行的情况下插入或更新...
【YashanDB 知识库】自关联外键插入数据时报错:YAS-02033 foreign key constraint violated parent key 问题现象使用如下的 sql 语句创建自关联外键表:drop table self_f_key;create table self_f_key(t1 number primary key not null..., t2 number);create index i_s_1 on self_f_key(t2);alter table...
Foreign key constraints also help define domain integrity, in that they define the range of potential and allowed values for aspecific column or columns. Domain integrity defines the validity of values in acolumn. The basic syntax for aforeign key constraint is: ...
添加外键约束:alter table 从表 add constraint 外键(形如:FK_从表_主表) foreign key 从表(外键字段) references 主表(主键字段); SQL语言共分为四大类:数据查询语言DQL,数据操纵语言DML,数据定义语言DDL,数据控制语言DCL。 1. 数据查询语言DQL 数据查询语言DQL基本结构是由SELECT子句,FROM子句,WHERE子句组成的...
primarykeyclustered,--主键 --1创建外键 dIdintnotnull constraintFK_MyUserInfo_tbDept foreignkey referencestbDept(dId), UserCIPchar(18)notnull constraintUQ_UserCIP_MyUserInfounique,--唯一约束 UserJSIDchar(6)notnull constraintUQ_userJSID_MyUserIdunique,--唯一约束 ...
新的可恢复功能,支持暂停和恢复 SQL Server 2022 和 Azure SQL 的正在运行的 ALTER TABLE ADD CONSTRAINT 操作。
SQL_ISV_CONSTRAINT_TABLE_USAGE = 标识约束(引用、唯一和断言)使用的表,并且由给定用户拥有。 (中级)SQL_ISV_DOMAIN_CONSTRAINTS = 标识可由给定用户访问的域约束(目录中的域)。 (中级)SQL_ISV_DOMAINS = 标识用户可以访问的目录中定义的域。 (中级)SQL_ISV_KEY_COLUMN_USAGE = 标识目录中定义的列,这些列...