foreign-keys

问题 How to insert foreign key into a table? I have two table (Info and WorkDetails) where WorkDetails has a foreign key which refer to Info. Is this the correct way to implement? MyDatabaseHelper.java public void onCreate(SQLiteDatabase db) { db.execSQL("create table "+TABLE_INFO+"(ID INTEGER PRIMARY KEY ,Name TEXT,Weather TEXT, Date DATETIME, Status Text)"); db.execSQL("create table"+TABLE_WORKDETAILS+"(ID INTEGER PRIMARY KEY , Project TEXT, WorkDescription TEXT, Per Text, TimeIn DATETIME,

问题 I'm having an issue with how Hibernate generates foreign key names when using the TABLE_PER_CLASS inheritance strategy: Foreign keys have random number appended when using Hibernate's TABLE_PER_CLASS inheritance So I'm wondering if I can simply replace the annotation with the following: @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) @Entity abstract class Item { @ManyToOne @ForeignKey(name="FK_ITEM_ORG_CHANGEME") @JoinColumn(name="ORG_ID") private Organization org } That way I

问题 I got information from SHOW ENGINE INNODB STATUS *** (1) TRANSACTION: TRANSACTION 0 2799914, ACTIVE 1 sec, process no 4106, OS thread id 139808903796480 inserting mysql tables in use 1, locked 1 LOCK WAIT 10 lock struct(s), heap size 1216, 7 row lock(s), undo log entries 3 MySQL thread id 4284, query id 2889649 localhost 127.0.0.1 test update INSERT INTO shipping ..... *** (1) WAITING FOR THIS LOCK TO BE GRANTED: RECORD LOCKS space id 0 page no 436366 n bits 88 index `PRIMARY` of table

问题 I want to create @ManyToOne mapping between Acount and Record. One account can have a lot of records. But i don't want to add Account field in Record class or vice versa. Could you please help me to describe this in annotations? @Entity public class Account { @Id ... getId(); } @Entity public class Record { @Id ... getId(); @????? ... getAccountId(); } 回答1: Mapping entities to tables is the way Hibernate usually works, if you don't want the Account class in Record you can simply define

问题 If I have a parent table and a child table, is it possible to multi-delete the rows in them without having a "ON DELETE CASCADE" constraint? In this example: create table a(id int primary key); create table b(id int primary key, a_id int, constraint fkb foreign key (a_id) references a(id)); Is it not possible to do something like this in order to delete rows in tables a and b? :-( delete a, b from b inner join a on a.id = b.a_id where a.id = ?; Error Code: 1451. Cannot delete or update a

问题 I'm new to setting up relational databases. I'm trying to create two tables in MySQL, a USER table and a COMPANY table. Both should be able to have multiple phone numbers associated with them, so I created a PHONE table and wanted to have a one-to-many relationship from both COMPANY to PHONE, and from USER to PHONE. There only seem to two options in what I am trying to do: Keep two foreign keys in PHONE, one referencing COMPANY, and one referencing USER. They would both default to NULL and

问题 I have a db that's structured with a supertype table as well as subtype tables like so: EVENT PatientId INTEGER, DateTime TEXT, EventTypeCode TEXT, PRIMARY KEY( PatientId, DateTime, EventTypeCode ) different types of events have their own tables and have the same primary key, except that it's foreign. EXERCISE PatientId INTEGER, DateTime TEXT, EventTypeCode TEXT, PRIMARY KEY( PatientId, DateTime, EventTypeCode ) ON CONFLICT IGNORE, CONSTRAINT "PrimaryKey" FOREIGN KEY ("PatientId",

问题 CREATE TABLE share( `User_1` VARCHAR(50) NOT NULL, `User_2` VARCHAR(50) NOT NULL, PRIMARY KEY(`User_1`,`User_2`), CONSTRAINT `fk_1` FOREIGN KEY (`User_1`) REFERENCES user(`Dev_ID`) ON DELETE RESTRICT ON UPDATE CASCADE , CONSTRAINT `fk_2` FOREIGN KEY (`User_2`) REFERENCES user(`Dev_ID`) ON DELETE RESTRICT ON UPDATE CASCADE ); I get this error: {Foreign key constraint is incorrectly formed } I want to make a link between user1 and user2. 来源： https://stackoverflow.com/questions/10076921/cant

问题 I'm a bit of a loss here. Basically I have these two Models: public class Player { public int PlayerId { get; set; } public string Name { get; set; } public virtual ICollection<Game> Games { get; set; } } public class Game { public int GameId { get; set; } public virtual Player PlayerBlack { get; set; } public virtual Player PlayerWhite { get; set; } } Now the Database Schema, EF Code First creates for me, is not correct because the Game table gets 3 Foreign Keys (Playerblack, PlayerWhite and

问题 I'm using phpMyAdmin for my database GUI and it's connecting to Yii Framework on my website. I wish for my products table for instance, to have a foreign key department_id which is a reference to the id field of my departments table. Unfortunately, I don't currently have the facility to set the foreign key up properly in phpMyAdmin, so department_id is just an indexed field. I cannot change the configuration of phpMyAdmin at the moment so it's stuck like it is without a foreign key and