【摘要】 下面的 SQL 在 "Orders" 表创建时在 "P_Id" 列上创建 FOREIGN KEY 约束:MySQL:CREATE TABLE Orders(O_Id int NOT NULL,OrderNo int NOT NULL,P_Id int,PRIMARY KEY (O_Id),FOREIGN KEY (P_Id) REFERENCES Persons(P_Id))SQL Serv..
SQL定义功能中,用CREATE TABLE建立表时,FOREIGN KEY...REFERENCES…短语的含义是A.说明主关键字B.建立表之间的联系C.说明有效性规则
CREATE TABLE role_groups ( `role_group_id` int(11) NOT NULL `AUTO_INCREMENT`, `name` varchar(20), `description` varchar(200), PRIMARY KEY (`role_group_id`)) ENGINE=InnoDB;CREATE TABLE IF NOT EXISTS `roles` ( `role_id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(50), `des...
sqlalchemy foreign key查询和backref 首先在mysql中创建两个表如下: mysql>createtableuser( idint,namevarchar(8) ,primarykey(id)); Query OK,0rows affected (0.01sec) mysql>createtableaddr(idint,valvarchar(100),user_idint,primarykey(id),foreignkey(user_id)referencesuser(id) ); Query OK,0rows ...
Here, thecustomer_idcolumn in theProductstable references theidcolumn in theCustomerstable. Foreign Key Syntax in SQL The syntax of the SQLFOREIGN KEYconstraint is: CREATE TABLE table_name ( column1 data_type, column2 data_type, ..., ...
sql server create foreign key in table design view(right click table and choose design), right click on a column, and select 'relationship', then create your foreign keys, sql, stop changes that require recreating table: select tools ->options-> designer, then remove checked from prevent ...
用SQL语句创建表,使用语句 CREATE TABLE对列的约束主要有 NOT NULL,UNIQUE,PRIMARY KEY, FOREIGN KEY等。定义表的删除与
错误失败Can't create table 'test.t2' (errno: 150)..这不会告诉任何人任何有用的东西,除了这是一个外键问题。但是跑SHOW ENGINE INNODB STATUS;它会说: --- LATEST FOREIGN KEY ERROR --- 130811 23:36:38 Error in foreign key constraint of table test/t2: FOREIGN KEY (t1_id) REFERENCES t1...
PRIMARYKEY(OrderID), FOREIGNKEY(PersonID)REFERENCESPersons(PersonID) ); SQL Server / Oracle / MS Access: CREATETABLEOrders ( OrderID intNOTNULLPRIMARYKEY, OrderNumber intNOTNULL, PersonID intFOREIGNKEYREFERENCESPersons(PersonID) ); To allow naming of aFOREIGN KEYconstraint, and for defining aFOR...
mysql外键(foreign key)的用法 在mysql中MyISAM和InnoDB存储引擎都支持外键(foreign key),但是MyISAM只能支持语法,却不能实际使用。下面通过例子记录下InnoDB中外键的使用方法: 创建主表: mysql> create table parent(id int not null,primary key(id)) engine=innodb;...