大约有 42,000 项符合查询结果（耗时：0.0502秒） [XML]
Foreign Key to multiple tables
...on your needs.
You could simply create two columns in Ticket, OwnedByUserId and OwnedByGroupId, and have nullable Foreign Keys to each table.
You could create M:M reference tables enabling both ticket:user and ticket:group relationships. Perhaps in future you will want to allow a single ticket to ...
Check whether an input string contains a number in javascript
My end goal is to validate an input field. The input may be either alphabetic or numeric.
12 Answers
...
Best Practice: Access form elements by HTML id or name attribute?
...
Give your form an id only, and your input a name only:
<form id="myform">
<input type="text" name="foo">
Then the most standards-compliant and least problematic way to access your input element is via:
document.getElementById...
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...
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...
MySQL INNER JOIN select only one row from second table
...
You need to have a subquery to get their latest date per user ID.
SELECT a.*, c.*
FROM users a
INNER JOIN payments c
ON a.id = c.user_ID
INNER JOIN
(
SELECT user_ID, MAX(date) maxDate
FROM payments
GROUP BY user_ID
) b ON c.user_ID = b....
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...
jQuery or CSS selector to select all IDs that start with some string [duplicate]
How can I select all elements whose id starts with "player_"?
4 Answers
4
...
Mysql order by specific ID values
...ible to sort in mysql by "order by" using predefined set of column values (ID) like: order by (ID=1,5,4,3) so I would get record 1, 5, 4, 3 in that order out?
...
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...