大约有 18,400 项符合查询结果（耗时：0.0320秒） [XML]
Computed / calculated / virtual / derived columns in PostgreSQL
...
, product bigint GENERATED ALWAYS AS (int1 * int2) STORED
);
db<>fiddle here
VIRTUAL generated columns may come with one of the next iterations. (Not in Postgres 13, yet) .
Related:
Attribute notation for function call gives error
Until then, you can emulate VIRTUAL generated colu...
Unknown column in 'field list' error on MySQL Update query
...
Try using different quotes for "y" as the identifier quote character is the backtick (“`”). Otherwise MySQL "thinks" that you point to a column named "y".
See also MySQL 5 Documentation
...
How do I escape a single quote?
...ML document that was using single-quotes arround attributes values ; so I didn't think this was actually valid ;; I just (once again) learnt something while answering a question ; so, thanks for those comments !
– Pascal MARTIN
Mar 11 '10 at 21:08
...
What are the best practices for using a GUID as a primary key, specifically regarding performance?
I have an application that uses GUID as the Primary Key in almost all tables and I have read that there are issues about performance when using GUID as Primary Key. Honestly, I haven't seen any problem, but I'm about to start a new application and I still want to use the GUIDs as the Primary Keys, b...
Generate .pem file used to set up Apple Push Notifications
...tribution section, then click "Continue" button.
Step 3: Select the App ID you want to use for your BYO app (How to Create An App ID), then click "Continue" to go to next step.
Step 4: Follow the steps "About Creating a Certificate Signing Request (CSR)" to create a Certificate Signing Request...
Build and Version Numbering for Java Projects (ant, cvs, hudson)
... edited Feb 18 '16 at 12:22
Guido
40.2k2424 gold badges111111 silver badges166166 bronze badges
answered Jan 11 '10 at 4:56
...
Focus Input Box On Load
...load?
You can just add the autofocus attribute to the input.
<input id="myinputbox" type="text" autofocus>
However, this might not be supported in all browsers, so we can use javascript.
window.onload = function() {
var input = document.getElementById("myinputbox").focus();
}
2) How...
How do I directly modify a Google Chrome Extension File? (.CRX)
...er of the extension you wish to modify. ( Named according to the extension ID, to find the ID of the extension, go to chrome://extensions/). Once copied, you have to remove the _metadata folder.
From chrome://extensions in Developer mode select Load unpacked extension... and select your copied ext...
Create a nonclustered non-unique index within the CREATE TABLE statement with SQL Server
...mary key and unique constraints are implemented in terms of an index is a side effect. To manage indexes, you have CREATE/ALTER/DROP INDEX, as you are well aware.
Why do you have a such a requirement as to add non-unique-non-clustered indexes in the CREATE TABLE statement?
Note that SQL Server 201...
How can I find the version of the Fedora I use?
... answered Feb 12 '09 at 9:31
David GrantDavid Grant
12.9k33 gold badges5151 silver badges6161 bronze badges
...