MySQL外键约束On Delete、On Update 使用外键实现 CreateTable:CREATETABLE`child` ( `par_id`int(11)NOTNULL, `child_id`int(11)NOTNULL,PRIMARYKEY(`par_id`,`child_id`),FOREIGNKEY(`par_id`)REFERENCES`parent` (`par_id`)ONDELETECASCADEONUPDATECASCADE) ENGINE=InnoDBDEFAULTCHARSET=utf8CreateTable:CRE...
InnoDB:支持事务。速度不如myISAM;mysql服务器崩溃后提供自动恢复;支持级联更新,级联删除; MEMORY:数据及索引存储在内存中;数据非持久;最快 2、事务:transaction,是一个最小的不可再分的工作单元。通常一个事务对应了一个完整的业务(如银行 转账)。而一个完整的业务需要批量的DML语句(insert,update,delete)共同联合...
insert into test_data values(1,'aaa') on duplicate key update id=id;Query OK, 0 rows affected (0.00 sec)insert into test_data values(1,'aaa') on duplicate key update id=id,name=name;Query OK, 0 rows affected (0.00 sec) insert into test_data values(4,'cc') on duplicate key upda...
在MySQL 中,INSERT ... ON DUPLICATE KEY UPDATE和UPDATE ... WHERE id IN (...)的处理和加锁顺序是根据不同的逻辑需求和性能考虑设计的: INSERT ... ON DUPLICATE KEY UPDATE按用户指定顺序处理,以符合用户预期,简化实现,并减少锁竞争。 UPDATE ... WHERE id IN (...)按索引顺序处理,以避免死锁,提高...
1 last_updated timestamp default current_timestamp on update current_timestamp, With this MySQL timestamp update syntax in your MySQL "create table" syntax, this timestamp field will be updated every time you issue a SQL UPDATE statement on this table....
DUPLICATE KEY UPDATE batch执行时出死锁错误背景知识一、 mysql insert 与 duplicate key:典型的插入语句:多条:INSERT INTO tablename...10) ON DUPLICATE KEY UPDATE data=data+10; UPDATE t...
mysql>UPDATE table SET c=c+1 WHERE a=1 OR b=2 LIMIT 1; 1. 1 如果a=1 OR b=2与多个行向匹配,则只有一个行被更新。通常,您应该尽量避免对带有多个唯一关键字的表使用ON DUPLICATE KEY子句。 您可以在UPDATE子句中使用VALUES(col_name)函数从INSERT...UPDATE语句的INSE...
// 插入冲突数据,执行update,当前最新id自增 insert into user(user_id,user_name,score) values(2,'marry',87) on duplicate key update score=87 // 插入一条新数据 insert into user(user_id,user_name,score) values(3,'kiti',99) 使用场景: 数据时常变更,需要定时同步到mysql中,主键/唯一键一般不...
The on delete works perfect but the on update works as if were on update restrict. I cannot change this PK when it referred through a foreign key. I Will post a short code (I've this problem in all tables). As you could seen prueba field is referred to id_grupo field, but if I...
Hi! Firstly, thanks for a great library, it is really intuitive and the documentation is excellent. However, I am having difficulty understanding why a constraint I am adding to my foreign keys is not being applied to the database schema...