If you really do have some pre-existing column in your data set that already does uniquely identify your row – then no, there’s no need for an extra ID column. The primary key however must be unique (in ALL circumstances) and cannot be empty (must be NOT NULL). In my 20+ years of experience in … Read more
Section 3 of RFC4122 provides the formal definition of UUID string representations. It’s 36 characters (32 hex digits + 4 dashes). Sounds like you need to figure out where the invalid 60-char IDs are coming from and decide 1) if you want to accept them, and 2) what the max length of those IDs might … Read more
I don’t think there is a blanket statement that you should only ever use a single primary key named id. Most people use a surrogate primary key as an auto generate int, because it isolates the primary key from ever needing to be changed, like if you make the PK the user name and they … Read more
You’ll have to use dynamic SQL for that, since ALTER TABLE does not accept variables or subqueries. CREATE TABLE PKTest ( ID INT PRIMARY KEY ) ; DECLARE @SQL VARCHAR(4000) SET @SQL = ‘ALTER TABLE PKTEST DROP CONSTRAINT |ConstraintName| ‘ SET @SQL = REPLACE(@SQL, ‘|ConstraintName|’, ( SELECT name FROM sysobjects WHERE xtype=”PK” AND parent_obj = … Read more
I think he is right ( for the wrong reason) because primary key cannot change, but username can change. So you should use userid because it wouldn’t change.
There is built-in Django way to achieve what you want. Add a field to the model of “custom page” with primary_key=True and default= name of key generation function, like this: class CustomPage(models.Model): … mykey = models.CharField(max_length=6, primary_key=True, default=pkgen) … Now, for every model instance page, page.pk becomes an alias for page.mykey, which is being auto-assigned … Read more
Add FOREIGN KEY (sale_id) REFERENCES Sale(sale_id) to each foreign table: CREATE TABLE Sale( sale_id CHAR(40), PRIMARY KEY(sale_id), discount DOUBLE, type VARCHAR(255), price DOUBLE ) ENGINE=INNODB; CREATE TABLE Normal_Sale( sale_id CHAR(40), PRIMARY KEY(sale_id), FOREIGN KEY (sale_id) REFERENCES Sale(sale_id) ) ENGINE=INNODB; CREATE TABLE Special_Sale( sale_id CHAR(40), PRIMARY KEY(sale_id), FOREIGN KEY (sale_id) REFERENCES Sale(sale_id) ) ENGINE=INNODB; Just make … Read more
In your app directory try this: python manage.py help sqlsequencereset Pipe it into psql like this to actually run the reset: python manage.py sqlsequencereset myapp1 myapp2 | psql Edit: here’s an example of the output from this command on one of my tables: BEGIN; SELECT setval(‘”project_row_id_seq”‘, coalesce(max(“id”), 1), max(“id”) IS NOT null) FROM “project_row”; COMMIT;
create table Table1 ( id varchar(2), name varchar(2), PRIMARY KEY (id) ) Create table Table1_Addr ( addid varchar(2), Address varchar(2), PRIMARY KEY (addid) ) Create table Table1_sal ( salid varchar(2),`enter code here` addid varchar(2), id varchar(2), PRIMARY KEY (salid), index(addid), index(id), FOREIGN KEY (addid) REFERENCES Table1_Addr(addid), FOREIGN KEY (id) REFERENCES Table1(id) )
To be clear, this question and answer are about using negative numbers for surrogate keys, not for natural keys. As far as I know, there are three reasons for considering it to be a bad practice. It violates the principle of least surprise. Some people assume all ID numbers are non-negative. Some people use negative … Read more