大约有 40,000 项符合查询结果（耗时：0.0300秒） [XML]
Replacing column values in a pandas DataFrame
...a column (the second 'female' in your w['female']['female']) doesn't mean "select rows where the value is 'female'". It means to select rows where the index is 'female', of which there may not be any in your DataFrame.
shar...
JPA eager fetch does not join
...
JPA doesn't provide any specification on mapping annotations to select fetch strategy. In general, related entities can be fetched in any one of the ways given below
SELECT => one query for root entities + one query for related mapped entity/collection of each root entity = (n+1) que...
SELECT * WHERE NOT EXISTS
...uming these tables should be joined on employeeID, use the following:
SELECT *
FROM employees e
WHERE NOT EXISTS
(
SELECT null
FROM eotm_dyn d
WHERE d.employeeID = e.id
)
You can join these tables with a LEFT JOIN keyword and filter out the...
Fluent and Query Expression — Is there any benefit(s) of one over other?
...me in fullNames
from name in fullName.Split()
orderby fullName, name
select name + " came from " + fullName;
Now compare this to the same thing in method syntax:
var query = fullNames
.SelectMany (fName => fName.Split().Select (name => new { name, fName } ))
.OrderBy (x => x.fN...
How to link a Facebook app with an existing fan page
...roducts").
Change your page name to mach your App name.
Go to your App and select "App Details"
Under "Contact Info" you will find "App Page". There you will be able to create a new page or if all went well, select your page from a list.
I found the info in the little question-mark next to "App pa...
Removing leading zeroes from a field in a SQL statement
... VARCHAR(10) field. So, for example, if the field contains '00001A', the SELECT statement needs to return the data as '1A'.
...
Why do you create a View in a database?
...e a View in their database? Why not just run a normal stored procedure or select?
25 Answers
...
What's the difference(s) between .ToList(), .AsEnumerable(), AsQueryable()?
...y we would typically write something like
var query = context.Observations.Select(o => o.Id)
.AsEnumerable().Select(x => MySuperSmartMethod(x))
ToList – which converts an IEnumerable<T> to a List<T> – is often used for this purpose as well. The advantage of...
In Eclipse, what can cause Package Explorer “red-x” error-icon when all Java sources compile without
...ers e.g __duplicatefile.java . To fix this, rightclick on the project and select : Show In > Navigator . Then delete the duplicate files with underscore and build your project.
– GraSim
May 29 '15 at 10:28
...
Group by in LINQ
... p in persons
group p.car by p.PersonId into g
select new { PersonId = g.Key, Cars = g.ToList() };
Or as a non-query expression:
var results = persons.GroupBy(
p => p.PersonId,
p => p.car,
(key, g) => new { PersonId = key, Cars = g.ToList() });
...