sql - SQL中的交叉外键

Question

我正在尝试创建 2 个带有交叉外键的表，但在创建它们时不允许我引用不存在的表。任何为 mysql 创建这样的表的方法，比如同时声明两个表或延迟外键的评估？

错误是 1005:无法在 mysql 5.0 上创建表 blocks.frm (errno 150)

SQL:

create table if not exists blocks( 
    id int unsigned not null auto_increment, 
    title varchar(100),
    defaultpage int unsigned not null, 
    foreign key(defaultpage) references pages(pageID), 
    primary key(id)) engine=innodb;

create table if not exists pages( 
    pageID int unsigned not null auto_increment, 
    title varchar(50) not null, 
    content blob,  
    blockid int unsigned not null, 
    foreign key(blockid) references block(id), 
    primary key(pageID) ) engine=innodb;

解决问题的正确方法是什么？

Answer 1

将 cletus 的答案(完全正确)带入代码...

create table if not exists pages( 
    pageID int unsigned not null auto_increment, 
    title varchar(50) not null, 
    content blob,  
    blockid int unsigned not null, 
    primary key(pageID) ) engine=innodb;

create table if not exists blocks( 
    id int unsigned not null auto_increment, 
    title varchar(100),
    defaultpage int unsigned not null, 
    foreign key(defaultpage) references pages(pageID), 
    primary key(id)) engine=innodb;

alter table pages add constraint fk_pages_blockid foreign key (blockid) references blocks (id);