大约有 47,000 项符合查询结果（耗时：0.0511秒） [XML]
Why would you use Expression rather than Func?
...y. Ie. you need database.data.Where(i => i.Id > 0) to be executed as SELECT FROM [data] WHERE [id] > 0. If you just pass in a Func, you've put blinders on your driver and all it can do is SELECT * and then once it's loaded all of that data into memory, iterate through each and filter out ev...
SQL, Postgres OIDs, What are they and why are they useful?
...ned system column oid will no longer be invisible by default. Performing a SELECT * will now include this column. Note that this extra “surprise” column may break naïvely written SQL code.
share
|
...
Drawing an image from a data URL to a canvas
...
in javascript , using jquery for canvas id selection :
var Canvas2 = $("#canvas2")[0];
var Context2 = Canvas2.getContext("2d");
var image = new Image();
image.src = "images/eye.jpg";
Context2.drawImage(image, 0, 0);
html5:
<canv...
Is there an Eclipse line-width marker?
...ou have to set it in the formatter: From menu [Window]-->[Preferences], select [Java]-->[Code Style]-->[Formatter], and then edit your formatter profile. In the tab page [Line wrapping], you can find a setting named "Maximum line width". Change this setting, and the print margin in Java sou...
When to Redis? When to MongoDB? [closed]
...e, writing stupid sql statements... not just one but freaking everywhere. "select this, select that". But in particular you remember the irritating WHERE clause. Where lastname equals "thornton" and movie equals "bad santa." Urgh. You think, "why don’t those dbas just do their job and give me som...
Getting the IP address of the current machine using Java
...getLocalHost</code> method does not
* specify the algorithm used to select the address returned under such circumstances, and will often return the
* loopback address, which is not valid for network communication. Details
* <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4665...
What is the difference between CascadeType.REMOVE and orphanRemoval in JPA?
... and remove the post entity:
Post post = entityManager.createQuery("""
select p
from Post p
join fetch p.comments
where p.id = :id
""", Post.class)
.setParameter("id", postId)
.getSingleResult();
entityManager.remove(post);
Hibernate is going to execute three delete statements:...
Attach IntelliJ IDEA debugger to a running Java process
...ation:
Run -> Edit Configurations...
Click the "+" in the upper left
Select the "Remote" option in the left-most pane
Choose a name (I named mine "remote-debugging")
Click "OK" to save:
JVM Options
The configuration above provides three read-only fields. These are options that tell the JV...
How to display unique records from a has_many through relationship?
...r the SQL DISTINCT stmt (e.g. has_many :products, :through => :orders, :select => "DISTINCT products.*). In the first case, ALL records are fetched and rails removes the duplicates for you. In the later case, only non-duplicate records are fetched from the db so it might offer better performan...
Apply CSS styles to an element depending on its child elements
...but this isn't possible.
You may want to consider looking at jQuery. Its selectors work very well with 'containing' types. You can select the div, based on its child contents and then apply a CSS class to the parent all in one line.
If you use jQuery, something along the lines of this would may w...