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MySQL foreign key constraints, cascade delete
I want to use foreign keys to keep the integrity and avoid orphans (I already use innoDB).
3 Answers
...
Want to find records with no associated records in Rails
Consider a simple association...
8 Answers
8
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SQLAlchemy IN clause
...
How about
session.query(MyUserClass).filter(MyUserClass.id.in_((123,456))).all()
edit: Without the ORM, it would be
session.execute(
select(
[MyUserTable.c.id, MyUserTable.c.name],
MyUserTable.c.id.in_((123, 456))
)
).fetchall()
select() takes two pa...
How do I search for an object by its ObjectId in the mongo console?
...Make sure the collection name is correct (case matters) and that the ObjectId is exact.
Documentation is here
> db.test.insert({x: 1})
> db.test.find() // no criteria
{ "_id" : ObjectId("4ecc05e55dd98a436ddcc47c"), "x" : 1 }
> db.test....
Accessing Object Memory Address
...
The Python manual has this to say about id():
Return the "identity'' of an object.
This is an integer (or long integer)
which is guaranteed to be unique and
constant for this object during its
lifetime. Two objects with
non-overlapping lifetimes may h...
How do I access my SSH public key?
...
cat ~/.ssh/id_rsa.pub or cat ~/.ssh/id_dsa.pub
You can list all the public keys you have by doing:
$ ls ~/.ssh/*.pub
share
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improve...
How to implement a many-to-many relationship in PostgreSQL?
...anguage) statements could look like this:
CREATE TABLE product (
product_id serial PRIMARY KEY -- implicit primary key constraint
, product text NOT NULL
, price numeric NOT NULL DEFAULT 0
);
CREATE TABLE bill (
bill_id serial PRIMARY KEY
, bill text NOT NULL
, billdate date NOT N...
How to implement the activity stream in a social network
.... Structure so that you can quickly grab a batch of activities by activity ID or by using a set of friend IDs with time constraints.
Publish the activity IDs to Redis whenever an activity record is created, adding the ID to an "activity stream" list for every user who is a friend/subscriber that sho...
Rails: Using greater than/less than with a where statement
I'm trying to find all Users with an id greater than 200, but I'm having some trouble with the specific syntax.
9 Answers
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Can an html element have multiple ids?
I understand that an id must be unique within an HTML/XHTML page.
18 Answers
18
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