大约有 40,000 项符合查询结果（耗时：0.0366秒） [XML]
How do I get a distinct, ordered list of names from a DataTable using LINQ?
...tainable, you can also split it up into multiple LINQ statements.
First, select your data into a new list, let's call it x1, do a projection if desired
Next, create a distinct list, from x1 into x2, using whatever distinction you require
Finally, create an ordered list, from x2 into x3, sorting by...
How to print from GitHub
...
Here's a super simple solution: Simply select all the text in the readme that you want to print, then print and choose "Only selected text".
This worked perfectly in Chrome (including images) and required no javascript or external sites or downloading or buildin...
updating table rows in postgres using subquery
...ery.customer,
address=subquery.address,
partn=subquery.partn
FROM (SELECT address_id, customer, address, partn
FROM /* big hairy SQL */ ...) AS subquery
WHERE dummy.address_id=subquery.address_id;
This syntax is not standard SQL, but it is much more convenient for this type of query...
How to achieve code folding effects in Emacs?
...on: C-h k C-x $
tells us that the above key combination is calling
set-selective-display, a function that takes one numerical argument
(the M-1 prefix passes 1 as the value of that argument) and,
unsurprisingly, sets the variable selective-display to the value of
that argument.
from mino...
Create code first, many to many, with additional fields in association table
...OfMembers = context.Members
.Where(m => m.LastName == "Smith")
.SelectMany(m => m.MemberComments.Select(mc => mc.Comment))
.ToList();
... or ...
var commentsOfMembers = context.MemberComments
.Where(mc => mc.Member.LastName == "Smith")
.Select(mc => mc.Comment)
...
Mysql: Select rows from a table that are not in another
How to select all rows in one table that do not appear on another?
8 Answers
8
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How to export table as CSV with headings on Postgresql?
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@arilwan psql -c "\COPY (SELECT * FROM mytable) TO STDOUT" > mytable.csv
– Juha Palomäki
Jun 6 '19 at 16:00
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MySQL select one column DISTINCT, with corresponding other columns
I want to select DISTINCT results from the FirstName column, but I need the corresponding ID and LastName .
12 Answe...
Map and Reduce in .NET
...ons. C# 3.5 and Linq already has it albeit under different names.
Map is Select:
Enumerable.Range(1, 10).Select(x => x + 2);
Reduce is Aggregate:
Enumerable.Range(1, 10).Aggregate(0, (acc, x) => acc + x);
Filter is Where:
Enumerable.Range(1, 10).Where(x => x % 2 == 0);
https://www...
Count number of records returned by group by
...
You can do both in one query using the OVER clause on another COUNT
select
count(*) RecordsPerGroup,
COUNT(*) OVER () AS TotalRecords
from temptable
group by column_1, column_2, column_3, column_4
share
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