大约有 46,000 项符合查询结果（耗时：0.0411秒） [XML]
Difference between EXISTS and IN in SQL?
...way to avoid counting:
--this statement needs to check the entire table
select count(*) from [table] where ...
--this statement is true as soon as one match is found
exists ( select * from [table] where ... )
This is most useful where you have if conditional statements, as exists can be a lot ...
Select count(*) from multiple tables
How can I select count(*) from two different tables (call them tab1 and tab2 ) having as result:
18 Answers
...
How to find third or nth maximum salary from salary table?
...you want a single) or DENSE_RANK(for all related rows):
WITH CTE AS
(
SELECT EmpID, EmpName, EmpSalary,
RN = ROW_NUMBER() OVER (ORDER BY EmpSalary DESC)
FROM dbo.Salary
)
SELECT EmpID, EmpName, EmpSalary
FROM CTE
WHERE RN = @NthRow
...
What are best practices that you use when writing Objective-C and Cocoa? [closed]
...aching of responses.
Also of interest, are some good iPhone specific tips from Joseph Mattiello (received in an iPhone mailing list). There are more, but these were the most generally useful I thought (note that a few bits have now been slightly edited from the original to include details offered ...
Will HTML5 allow web apps to make peer-to-peer HTTP connections?
...ere is an informed answer:
HTML 5 plans to allow peer to peer connections from javascript, but these connections WILL NOT BE RAW TCP.
The complete spec can be found at http://dev.w3.org/html5/websockets/
jrh
EDIT: with specific reference to peer to peer connections, check out these links:
Rega...
How to select a drop-down menu value with Selenium using Python?
I need to select an element from a drop-down menu.
13 Answers
13
...
How to declare variable and use it in the same Oracle SQL script?
...; exec :name := 'SALES'
PL/SQL procedure successfully completed.
SQL> select * from dept
2 where dname = :name
3 /
DEPTNO DNAME LOC
---------- -------------- -------------
30 SALES CHICAGO
SQL>
A VAR is particularly useful when we want to call a stored...
MySQL - Get row number on select
Can I run a select statement and get the row number if the items are sorted?
5 Answers
...
How do you use the “WITH” clause in MySQL?
...s mentioned, you provided a poor example - there's no need to perform a subselect if you aren't altering the output of the columns in any way:
SELECT *
FROM ARTICLE t
JOIN USERINFO ui ON ui.user_userid = t.article_ownerid
JOIN CATEGORY c ON c.catid = t.article_categoryid
WHERE t....
Checking if a double (or float) is NaN in C++
...l isnormal(T t);
If you have time then have a look at whole Math toolkit from Boost, it has many useful tools and is growing quickly.
Also when dealing with floating and non-floating points it might be a good idea to look at the Numeric Conversions.
...