大约有 47,000 项符合查询结果（耗时：0.0305秒） [XML]
Distinct in Linq based on only one field of the table
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Try this:
table1.GroupBy(x => x.Text).Select(x => x.FirstOrDefault());
This will group the table by Text and use the first row from each groups resulting in rows where Text is distinct.
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Count work days between two dates
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For workdays, Monday to Friday, you can do it with a single SELECT, like this:
DECLARE @StartDate DATETIME
DECLARE @EndDate DATETIME
SET @StartDate = '2008/10/01'
SET @EndDate = '2008/10/31'
SELECT
(DATEDIFF(dd, @StartDate, @EndDate) + 1)
-(DATEDIFF(wk, @StartDate, @EndDate) *...
-didSelectRowAtIndexPath: not being called
...de a tab view. In my UITableViewController , I implemented -tableView:didSelectRowAtIndexPath: , but when I select a row at runtime, the method isn't being called. The table view is being populated though, so I know that other tableView methods in my controller are being called.
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MySQL - UPDATE query based on SELECT Query
...can go here
ANSI SQL syntax:
UPDATE tableA SET validation_check =
(SELECT if(start_DTS > end_DTS, 'VALID', '') AS validation_check
FROM tableA
INNER JOIN tableB ON name_A = name_B
WHERE id_A = tableA.id_A)
Pick whichever one seems most natural to you.
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Python SQL query string formatting
...qualified a somewhere between Option 2 and Option 4
Code Sample:
sql = ("SELECT field1, field2, field3, field4 "
"FROM table "
"WHERE condition1=1 "
"AND condition2=2;")
Works as well with f-strings:
fields = "field1, field2, field3, field4"
table = "table"
conditions = "co...
Fetch the row which has the Max value for a column
... multiple rows for the userid where the maximum date is on multiple rows.
select userid,
my_date,
...
from
(
select userid,
my_date,
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max(my_date) over (partition by userid) max_my_date
from users
)
where my_date = max_my_date
"Analytic functions rock"
Edi...
LINQ Using Max() to select a single row
I'm using LINQ on an IQueryable returned from NHibernate and I need to select the row with the maximum value(s) in a couple of fields.
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How to report an error from a SQL Server user-defined function
... For an inline-table-valued-function where the RETURN is a simple select, this alone doesn't work because nothing is returned - not even null, and in my case I wanted to throw an error when nothing was found. I didn't want to break down the inline function into a multi-statment one for obv...
What are the differences between Chosen and Select2?
Chosen and Select2 are the two more popular libraries for extending selectboxes.
11 Answers
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MySQL Orderby a number, Nulls last
...Place a minus sign (-) before the column name and switch the ASC to DESC:
SELECT * FROM tablename WHERE visible=1 ORDER BY -position DESC, id DESC
It is essentially the inverse of position DESC placing the NULL values last but otherwise the same as position ASC.
A good reference is here http://t...