Function object to remove a foreign key constraint from the referenced_set of the referenced table. The foreign key object is also removed from the dictionary cache. The foreign key constraint is not removed from the foreign_set of the table containing the constraint. ...
CONSTRAINT emlyee_dept_fk FOREIGN KEY(deptId) REFERENCES dept(id) 约束 外键名称 外键 参照 参考表(参考字段) 外键 多表的设计 一对多:(非常多) CREATE TABLE department( id int primary key, name varchar(100), floor int ); CREATE TABLE employee( id int primary key, name varchar(100), salary ...
Dropping the foreign key constraint by constraint name does not work either: mysql> create table ref (ref_id int unsigned not null, something varchar(30), primary key(ref_id)); Query OK, 0 rows affected (0.27 sec) mysql> create table test (test_id int unsigned not null auto_increment,...
CREATE TABLE major( id INT PRIMARY KEY, major_name VARCHAR(20) ); DROP TABLE IF EXISTS myStuinfo; CREATE TABLE myStuinfo( id INT PRIMARY KEY AUTO_INCREMENT, cname VARCHAR(20), majorId INT, CONSTRAINT majorid_to_major FOREIGN KEY (majorid) REFERENCES major(id) ON DELETE CASCADE ); 1. ...
不同的是MySQL会自动为所有表的主键进行索引,但是外键字段必须由用户进行明确的索引。用于外键关系的字段必须在所有的参照表中进行明确地索引,InnoDB不能自动地创建索引。 2、外键可以是一对一的,一... 浪里飞 0 43668 foreign key constraint fails错误的原因...
ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key constraint fails (confluence_qa.CONTENTPROPERTIES, CONSTRAINT FK3fly21xfk13rqh63txw2t6k2v FOREIGN KEY (CONTENTID) REFERENCES CONTENT (CONTENTID)) ERROR 1451 (23000): Cannot delete or update a parent row: a foreign key...
MySQL allows table columns to be created with the NOT NULL constraint. This implies that the field needs to be populated with a value that cannot be the NULL value. In some cases we may need to remove this constraint. This is achieved using the following command: ...
(`SPACEID`) REFERENCES `SPACES` (`SPACEID`); alter table PAGETEMPLATES add CONSTRAINT FKBC7CE96A17D4A070 FOREIGN KEY (`PREVVER`) REFERENCES `PAGETEMPLATES` (`TEMPLATEID`); alter table PAGETEMPLATES add CONSTRAINT FKBC7CE96AB2DC6081 FOREIGN KEY (`SPACEID`) REFERENCES `SPACES` (`SPACE...
foreach ($schema->getForeignKeys($table) as $foreignKeyConstraint) { foreach ($foreignKeyConstraint['columns'] as $columnName) { $this->foreignKeyConstraintsColumns[] = $columnName; } } 4 changes: 2 additions & 2 deletions 4 tests/Console/ModelsCommand/AllowGlobDirectory/__snapshots__/Test...
string.Substring(1,2) Remove(int startIndex) 删除此字符串中从指定位置到最后位置的所有字符。 Remove(int startIndex, int length) 从此实例中的指定位置开始删除指定数目的字符。 字母大小写的转换, string.ToLower() string.ToUpper() 正则表达式的用法...