大约有 43,000 项符合查询结果（耗时：0.0474秒） [XML]
What is the difference between the states selected, checked and activated in Android?
...below added):
... For example, in a list view with single or multiple selection
enabled, the views in the current selection set are activated. (Um,
yeah, we are deeply sorry about the terminology here.) The activated
state is propagated down to children of the view it is set on.
So here...
SQL Server CTE and recursion example
...The query finds all root nodes as described by WHERE ManagerID IS NULL
SELECT EmployeeID, FirstName, LastName, ManagerID, 1
FROM Employees
WHERE ManagerID IS NULL
-->>>>>>>>>>Block 1>>>>>>>>>>>>>>>>>
UNI...
Caveats of select/poll vs. epoll reactors in Twisted
...o based apps ) leads me to believe that ePoll is a natural replacement for Select and Poll based networking, especially with Twisted. Which makes me paranoid, its pretty rare for a better technique or methodology not to come with a price.
...
How to generate a range of numbers between two numbers?
...
Select non-persisted values with the VALUES keyword. Then use JOINs to generate lots and lots of combinations (can be extended to create hundreds of thousands of rows and beyond).
SELECT ones.n + 10*tens.n + 100*hundreds.n +...
Is there a way to access the “previous row” value in a SELECT statement?
...d to order by some column for this to be meaningful. Something like this:
select t1.value - t2.value from table t1, table t2
where t1.primaryKey = t2.primaryKey - 1
If you know how to order things but not how to get the previous value given the current one (EG, you want to order alphabetically) ...
How to select a single field for all documents in a MongoDB collection?
...nt such as:
db.student.find({}, {roll:1, _id:0})
The above statement will select all documents in the students collection, and the returned document will return only the roll field (and exclude the _id).
If we don't mention _id:0 the fields returned will be roll and _id. The '_id' field is always d...
How to return only the Date from a SQL Server DateTime datatype
...
On SQL Server 2008 and higher, you should CONVERT to date:
SELECT CONVERT(date, getdate())
On older versions, you can do the following:
SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, @your_date))
for example
SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE()))
gives me
2008-09-22 00:...
Ruby on Rails form_for select field with class
I am beating my head against the wall on this one. I want to make a simple select tag using the f.select tag but nothing I do works. I put an example below:
...
Insert into … values ( SELECT … FROM … )
...
Try:
INSERT INTO table1 ( column1 )
SELECT col1
FROM table2
This is standard ANSI SQL and should work on any DBMS
It definitely works for:
Oracle
MS SQL Server
MySQL
Postgres
SQLite v3
Teradata
DB2
Sybase
Vertica
HSQLDB
H2
AWS RedShift
SA...
NOT IN vs NOT EXISTS
...llow NULLs the NOT IN will be treated identically to the following query.
SELECT ProductID,
ProductName
FROM Products p
WHERE NOT EXISTS (SELECT *
FROM [Order Details] od
WHERE p.ProductId = od.ProductId)
The exact plan may vary but for my examp...