大约有 30,000 项符合查询结果（耗时：0.0421秒） [XML]
SQL RANK() versus ROW_NUMBER()
...bout the differences between these. Running the following SQL gets me two idential result sets. Can someone please explain the differences?
...
MySQL和MongoDB设计实例进行对比 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...数表来单独保存。
CREATE TABLE IF NOT EXISTS `mobiles` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`name` VARCHAR(100) NOT NULL,
`brand` VARCHAR(100) NOT NULL,
PRIMARY KEY (`id`)
);
CREATE TABLE IF NOT EXISTS `mobile_params` (
`id` int(10) unsigned NOT NUL...
两种js滑动门(tab切换)效果 - 源码下载 - 清泛网 - 专注C/C++及内核技术
...d: #fff;
text-align: center;
margin: 0;
}
.nTab{
float: left;
width: 960px;
margin: 0 auto;
border-bottom:1px #AACCEE solid;
background:#d5d5d5;
background-position:left;
background-repeat:repeat-y;
margin-bottom:2px;
}
.nTab .TabTitle{
clear: both;
height: 22px;
ov...
Trigger a button click with JavaScript on the Enter key in a text box
...t to trigger the button's click event when the Enter key is pressed inside the text box?
30 Answers
...
Drop a temporary table if it exists
... IF EXISTS ##CLIENTS_KEYWORD
On previous versions you can use
IF OBJECT_ID('tempdb..##CLIENTS_KEYWORD', 'U') IS NOT NULL
/*Then it exists*/
DROP TABLE ##CLIENTS_KEYWORD
CREATE TABLE ##CLIENTS_KEYWORD
(
client_id INT
)
You could also consider truncating the table instead rather than dropping ...
how to add records to has_many :through association in rails
...mer.new(params[:customer])
@cust.houses << House.find(params[:house_id])
Or when creating a new house for a customer:
@cust = Customer.new(params[:customer])
@cust.houses.create(params[:house])
You can also add via ids:
@cust.house_ids << House.find(params[:house_id])
...
JavaScript check if variable exists (is defined/initialized)
...initialized is better/correct?
(Assuming the variable could hold anything (string, int, object, function, etc.))
28 Answers...
Can a constructor in Java be private?
...e constructor helps code reuse.
public class MyClass {
private final String value;
private final String type;
public MyClass(int x){
this(Integer.toString(x), "int");
}
public MyClass(boolean x){
this(Boolean.toString(x), "boolean");
}
public ...
Trouble comparing time with RSpec
... do API testing with pure RSpec)
As for "post-db-times" I guess you mean string that is generated after saving to DB. I would suggest decouple this case to 2 expectations (one ensuring hash structure, second checking the time) So you can do something like:
hash = {mytime: Time.now.to_s(:db)}
expe...
How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...em in useful detail.
In general you must choose between two options:
Individual insert/update operations in a retry loop; or
Locking the table and doing batch merge
Individual row retry loop
Using individual row upserts in a retry loop is the reasonable option if you want many connections concurre...