大约有 40,000 项符合查询结果（耗时：0.0403秒） [XML]
List comprehension in Ruby
..._ARRAY.map{|x| x % 2 == 0 ? x * 3 : nil}.compact
end
end
def test_select_map
1000.times do
TEST_ARRAY.select{|x| x % 2 == 0 }.map{|x| x * 3}
end
end
def test_inject
1000.times do
TEST_ARRAY.inject([]) {|all, x| all << x*3 if x % 2 == 0; all }
end
end...
SQL Server IN vs. EXISTS Performance
...execution operation, to get their results.
An example:
Query 1 ( plan )
select * from dt where dt.customer in (select c.code from customer c where c.active=0)
Query 2 ( plan )
select * from dt where exists (select 1 from customer c where c.code=dt.customer and c.active=0)
...
Visual Studio C# statement collapsing
...have to turn off automatic outlining.
Right click in your code window and select (Outlining | Stop Outlining)
Then, select some text, right click and select (Outlining | Hide Selection)
When you turn on automatic outlining again, your custom "Regions" will no longer collapse.
...
What's the equivalent for eclipse's ALT+UP/DOWN (move line) in Visual Studio?
In Eclipse, selecting a line and pressing Alt + ↑ / ↓ will move the line up and down, a quick way to avoid copy&paste.
Is there an equivalent in Visual Studio?
...
Is the NOLOCK (Sql Server hint) bad practice?
...
With NOLOCK hint, the transaction isolation level for the SELECT statement is READ UNCOMMITTED. This means that the query may see dirty and inconsistent data.
This is not a good idea to apply as a rule. Even if this dirty read behavior is OK for your mission critical web based app...
Remove empty space before cells in UITableView
...e first one.
Here's how to change this behavior:
a) Interface Builder
Select the view controller
Open Attributes inspector
There's a property called "Adjust scroll view insets" in IB's attribute inspector (when a view controller is selected) which is on by default. Uncheck this option:
(Image...
How to debug Spring Boot application with Eclipse?
...dd that Remote Java Application configuration in Run/Debug configurations, select the port/address you defined when starting your app, and then you are free to debug.
share
|
improve this answer
...
Use '=' or LIKE to compare strings in SQL?
...
To see the performance difference, try this:
SELECT count(*)
FROM master..sysobjects as A
JOIN tempdb..sysobjects as B
on A.name = B.name
SELECT count(*)
FROM master..sysobjects as A
JOIN tempdb..sysobjects as B
on A.name LIKE B.name
Comparing strings with '=' is muc...
Naming of ID columns in database tables
...!)and forget to change the alias in the join condition.
So you now have
select t1.field1, t2.field2, t3.field3
from table1 t1
join table2 t2 on t1.id = t2.table1id
join table3 t3 on t1.id = t3.table2id
when you meant
select t1.field1, t2.field2, t3.field3
from table1 t1
join table2 t2 on t1...
Why does using an Underscore character in a LIKE filter give me all the results?
...
You have to escape the wildcard character, in sql-server with [] around:
SELECT m.*
FROM Manager m
WHERE m.managerid LIKE '[_]%'
AND m.managername LIKE '%[_]%'
See: LIKE (Transact-SQL)
Demo
share
|
...