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Difference Between One-to-Many, Many-to-One and Many-to-Many?
... One Person Has Many Skills, a Skill is not reused between Person(s)
Unidirectional: A Person can directly reference Skills via its Set
Bidirectional: Each "child" Skill has a single pointer back up to the
Person (which is not shown in your code)
Many-to-Many: One Person Has Many Skil...
完美解决phpcms批量移动内容后，新闻心情、评论排行等不更新的问题 - 更多...
...空链接了（原url已删除了）。
原因：内容移动后，catid发生了变化，而comment、mood相关的表中catid没有更新。
解决方法：只需修改一个文件搞定 phpcms/modules/content/content.php
/**
* 批量移动文章
*/
public fun...
Rails: Default sort order for a rails model?
... rails 4 there are deprecation warning when using #scope without passing a callable object. For example scope :red, where(color: 'red') should be changed to scope :red, -> { where(color: 'red') }.
As a side note, when used incorrectly, default_scope can be misused/abused.
This is mainly about wh...
Delete duplicate records in SQL Server?
Consider a column named EmployeeName table Employee . The goal is to delete repeated records, based on the EmployeeName field.
...
How can I get sin, cos, and tan to use degrees instead of radians?
...ultiply the input by Math.PI/180 to convert from degrees to radians before calling the system trig functions.
You could also define your own functions:
function sinDegrees(angleDegrees) {
return Math.sin(angleDegrees*Math.PI/180);
};
and so on.
...
How to delete from select in MySQL?
...ner subquery result (looks rather hacky, though):
DELETE FROM posts WHERE id IN (
SELECT * FROM (
SELECT id FROM posts GROUP BY id HAVING ( COUNT(id) > 1 )
) AS p
)
Or use joins as suggested by Mchl.
sh...
How do I perform the SQL Join equivalent in MongoDB?
... The new $lookup operator added to the aggregation pipeline is essentially identical to a left outer join:
https://docs.mongodb.org/master/reference/operator/aggregation/lookup/#pipe._S_lookup
From the docs:
{
$lookup:
{
from: <collection to join>,
localField: <fiel...
How do I find a stored procedure containing ?
...TION LIKE '%Foo%'
AND ROUTINE_TYPE='PROCEDURE'
SELECT OBJECT_NAME(id)
FROM SYSCOMMENTS
WHERE [text] LIKE '%Foo%'
AND OBJECTPROPERTY(id, 'IsProcedure') = 1
GROUP BY OBJECT_NAME(id)
SELECT OBJECT_NAME(object_id)
FROM sys.sql_modules
WHERE OBJECTPROPERTY(object_...
How to annotate MYSQL autoincrement field with JPA annotations
...
To use a MySQL AUTO_INCREMENT column, you are supposed to use an IDENTITY strategy:
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
private Long id;
Which is what you'd get when using AUTO with MySQL:
@Id @GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
Which is a...
How to get multiple counts with one SQL query?
...ally the same thing as a PIVOT function in some RDBMS:
SELECT distributor_id,
count(*) AS total,
sum(case when level = 'exec' then 1 else 0 end) AS ExecCount,
sum(case when level = 'personal' then 1 else 0 end) AS PersonalCount
FROM yourtable
GROUP BY distributor_id
...