大约有 18,339 项符合查询结果（耗时：0.0264秒） [XML]
Mapping many-to-many association table with extra column(s)
... So I'll show you how it should look like.
If you make the relationships bidirectional, you should thus have
class User {
@OneToMany(mappedBy = "user")
private Set<UserService> userServices = new HashSet<UserService>();
}
class UserService {
@ManyToOne
@JoinColumn(name...
Find all records which have a count of an association greater than zero
... To remove the duplicates, use
Project.joins(:vacancies).group('projects.id')
UPDATE:
As pointed out by @Tolsee, you can also use distinct.
Project.joins(:vacancies).distinct
As an example
[10] pry(main)> Comment.distinct.pluck :article_id
=> [43, 34, 45, 55, 17, 19, 1, 3, 4, 18, 44, ...
SQL join: selecting the last records in a one-to-many relationship
...mmend solving it:
SELECT c.*, p1.*
FROM customer c
JOIN purchase p1 ON (c.id = p1.customer_id)
LEFT OUTER JOIN purchase p2 ON (c.id = p2.customer_id AND
(p1.date < p2.date OR (p1.date = p2.date AND p1.id < p2.id)))
WHERE p2.id IS NULL;
Explanation: given a row p1, there should be no ro...
How to reset postgres' primary key sequence when it falls out of sync?
...
-- Login to psql and run the following
-- What is the result?
SELECT MAX(id) FROM your_table;
-- Then run...
-- This should be higher than the last result.
SELECT nextval('your_table_id_seq');
-- If it's not higher... run this set the sequence last to your highest id.
-- (wise to run a quick pg...
javascript find and remove object in array based on key value
...been trying several approaches on how to find an object in an array, where ID = var, and if found, remove the object from the array and return the new array of objects.
...
When and why I should use session_regenerate_id()?
Why and when should I use the session_regenerate_id() function in php?
Should I always use it after I use the session_start() ?
I've read that I have to use it to prevent session fixation, is this the only reason?
...
How can I list all foreign keys referencing a given table in SQL Server?
...s...
select
t.name as TableWithForeignKey,
fk.constraint_column_id as FK_PartNo, c.
name as ForeignKeyColumn
from
sys.foreign_key_columns as fk
inner join
sys.tables as t on fk.parent_object_id = t.object_id
inner join
sys.columns as c on fk.parent_object_id = c.object...
Retrieving the last record in each group - MySQL
..._messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITION BY name ORDER BY id DESC) AS rn
FROM messages AS m
)
SELECT * FROM ranked_messages WHERE rn = 1;
Below is the original answer I wrote for this question in 2009:
I write the solution this way:
SELECT m1.*
FROM messages m1 LEFT JOIN mes...
Get specific object by id from array of objects in AngularJS
...s to get only one object from the array. So I d like for example Item with id 1.
17 Answers
...
How to create relationships in MySQL
...e innodb you can create it like this:
CREATE TABLE accounts(
account_id INT NOT NULL AUTO_INCREMENT,
customer_id INT( 4 ) NOT NULL ,
account_type ENUM( 'savings', 'credit' ) NOT NULL,
balance FLOAT( 9 ) NOT NULL,
PRIMARY KEY ( account_id ),
FOREIGN KEY (customer_id) REFERE...