大约有 40,000 项符合查询结果（耗时：0.0236秒） [XML]
Reshaping data.frame from wide to long format
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Here is another example showing the use of gather from tidyr. You can select the columns to gather either by removing them individually (as I do here), or by including the years you want explicitly.
Note that, to handle the commas (and X's added if check.names = FALSE is not set), I am also us...
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) *...
Get day of week in SQL Server 2005/2008
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Use DATENAME or DATEPART:
SELECT DATENAME(dw,GETDATE()) -- Friday
SELECT DATEPART(dw,GETDATE()) -- 6
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Checking oracle sid and database name
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I presume SELECT user FROM dual; should give you the current user
and SELECT sys_context('userenv','instance_name') FROM dual; the name of the instance
I believe you can get SID as SELECT sys_context('USERENV', 'SID') FROM DUAL;
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SQL selecting rows by most recent date
...eturns a result set with ChargeId, ChargeType, and MostRecentServiceMonth
SELECT
CHARGEID,
CHARGETYPE,
MAX(SERVICEMONTH) AS "MostRecentServiceMonth"
FROM INVOICE
GROUP BY CHARGEID, CHARGETYPE
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Search text in stored procedure in SQL Server
...t the schema name by adding SCHEMA_NAME(o.schema_id) AS Schema_Name to the select clause.
– patricus
Jul 7 '16 at 15:07
6
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ASP.NET MVC How to convert ModelState errors to json
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You can put anything you want to inside the select clause:
var errorList = (from item in ModelState
where item.Value.Errors.Any()
select item.Value.Errors[0].ErrorMessage).ToList();
EDIT: You can extract multiple errors into separate list items by a...
What does it mean when a CSS rule is grayed out in Chrome's element inspector?
... because one or more rules from the set are being applied to the currently selected DOM node.
I guess, for the sake of completeness, dev tools shows all the rules from that set, whether they are applied or not.
In the case where a rule is applied to the currently selected element due to inheritance...
Can someone explain collection_select to me in clear, simple terms?
I am going through the Rails API docs for collection_select and they are god-awful.
2 Answers
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How to get the top 10 values in postgresql?
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For this you can use limit
select *
from scores
order by score desc
limit 10
If performance is important (when is it not ;-) look for an index on score.
Starting with version 8.4, you can also use the standard (SQL:2008) fetch first
select *
from...