foreign-keys

I am creating a new table inside mysql and I am trying to add a foreign key constraint to one of the fields. CREATE TABLE `onlineorder` ( `receiptid` varchar(10) NOT NULL default '', `delivereddate` date default NULL, `cid` int(10) NOT NULL, `card#` int(10) default NULL, `expire` date default NULL, PRIMARY KEY (`receiptid`), FOREIGN KEY (receiptid) REFERENCES purchase ) ENGINE=MyISAM DEFAULT CHARSET=latin1; However, after it creates it, I go into phpMyAdmin and export the table. and it seems like the foreign key constraint has disappeared. CREATE TABLE `onlineorder` ( `receiptid` varchar(10)

My application loads lots of data from a database into a complex data structure. The in-memory data structure ressembles the structure of the database, which means that if the database contains the following tables: table A, key is A1 table B, key is B1, one of the columns is a foreign key to [the key of] table A table C, key is C1, one of the columns is a foreign key to [the key of] table B Then I have classes A, B and C, and: a data member of B (B::m_a) is a pointer to A a data member of C (C::m_b) is a pointer to B This implies that if I load the database, that I have to load it in the

my goal is to create a custom user model in Django 1.5 # myapp.models.py from django.contrib.auth.models import AbstractBaseUser class MyUser(AbstractBaseUser): email = models.EmailField( verbose_name='email address', max_length=255, unique=True, db_index=True, ) first_name = models.CharField(max_length=30, blank=True) last_name = models.CharField(max_length=30, blank=True) company = models.ForeignKey('Company') ... USERNAME_FIELD = 'email' REQUIRED_FIELDS = ['company'] I can't create a super user because of the company field (models.ForeignKey('Company') (python manage.py createsuperuser). My

Simple question: I'm new to Laravel. I have this migration file: Schema::create('lists', function(Blueprint $table) { $table->increments('id'); $table->string('title', 255); $table->integer('user_id')->unsigned(); $table->foreign('user_id')->references('id')->on('users'); $table->timestamps(); }); I want to update it to add onDelete('cascade') . What's the best way to do this? Firstly you have to make your user_id field an index: $table->index('user_id'); After that you can create a foreign key with an action on cascade: $table->foreign('user_id')->references('id')->on('users')->onDelete(

I've got a table that is supposed to track days and costs for shipping product from one vendor to another. We (brilliantly :p) stored both the shipping vendors (FedEx, UPS) with the product handling vendors (Think... Dunder Mifflin) in a "VENDOR" table. So, I have three columns in my SHIPPING_DETAILS table that all reference VENDOR.no. For some reason MySQL isn't letting me define all three as foreign keys. Any ideas? CREATE TABLE SHIPPING_GRID( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY COMMENT 'Unique ID for each row', shipping_vendor_no INT(6) NOT NULL COMMENT 'Foreign key to VENDOR.no for

Suppose I have a field f in my model defined as follows as a foreign key: f = models.ForeignKey(AnotherModel) When Django syncs database, the filed created in db will be called f_id , automatically suffixed with '_id'. The problem is I want this field in db named exactly as what I defined in model, f in this case. How can I achieve that? Simon Liu Well it turns out there's a keyword argument called db_column . If you want the field called 'f' in the database is just as simple as: f = models.ForeignKey(AnotherModel, db_column='f') Further reference: The name of the database column to use for

We're using polymorphic associations in our application. We've run into the classic problem: we encountered an invalid foreign key reference, and we can't create a foreign key constraint, because its a polymorphic association. That said, I've done a lot of research on this. I know the downsides of using polymorphic associations, and the upsides. But I found what seems to be a decent solution: http://blog.metaminded.com/2010/11/25/stable-polymorphic-foreign-key-relations-in-rails-with-postgresql/ This is nice, because you get the best of both worlds. My concern is the data duplication. I don't

So I'm attempting to add a new foreign key to one of my tables as such: ALTER TABLE `UserTransactions`.`ExpenseBackTransactions` ADD CONSTRAINT `FK_EBTx_CustomAccountID` FOREIGN KEY (`CustomAccountID` ) REFERENCES `UserTransactions`.`CustomAccounts` (`CustomAccountID`) ON DELETE NO ACTION ON UPDATE NO ACTION, ADD INDEX `FK_EBTx_CustomAccountID` (`CustomAccountID` ASC) ; and I keep getting the following error: Error Code: 1005 Can't create table './UserTransactions/#sql-187a_29.frm' (errno: 150) I've done quite a bit of changes in the past to this and other tables, and this is the first time I