大约有 47,000 项符合查询结果（耗时：0.0105秒） [XML]
How to reshape data from long to wide format
...mes(df) <- unique(dat1$name)
df
sqldf package:
library(sqldf)
sqldf('SELECT name,
MAX(CASE WHEN numbers = 1 THEN value ELSE NULL END) x1,
MAX(CASE WHEN numbers = 2 THEN value ELSE NULL END) x2,
MAX(CASE WHEN numbers = 3 THEN value ELSE NULL END) x3,
MAX(CASE WHEN numbe...
Efficiently convert rows to columns in sql server
...ou can use the PIVOT function to transform the data from rows to columns:
select Firstname, Amount, PostalCode, LastName, AccountNumber
from
(
select value, columnname
from yourtable
) d
pivot
(
max(value)
for columnname in (Firstname, Amount, PostalCode, LastName, AccountNumber)
) piv;
S...
Read data from SqlDataReader
...you use indexes like reader.GetString(0) will it use the first column you selected in your query or the firstt column on the table. I have a table with 3 columns in order: ID, Dir, Email. My command selects dir and email. Will reader.GetStrting(0) retrieve dir or ID? Are the indexes based off t...
Query to list number of records in each table in a database
...
If you're using SQL Server 2005 and up, you can also use this:
SELECT
t.NAME AS TableName,
i.name as indexName,
p.[Rows],
sum(a.total_pages) as TotalPages,
sum(a.used_pages) as UsedPages,
sum(a.data_pages) as DataPages,
(sum(a.total_pages) * 8) / 1024 as To...
How do we count rows using older versions of Hibernate (~2009)?
...eturn int and use this form:
int count = ((Long)getSession().createQuery("select count(*) from Book").uniqueResult()).intValue();
share
|
improve this answer
|
follow
...
Connecting overloaded signals and slots in Qt 5
...alueChanged(QString). From Qt 5.7, there are helper functions provided to select the desired overload, so you can write
connect(spinbox, qOverload<int>(&QSpinBox::valueChanged),
slider, &QSlider::setValue);
For Qt 5.6 and earlier, you need to tell Qt which one you want to p...
Getting only Month and Year from SQL DATE
...o 'discard' the Days, Hours, etc
- Leaving a year/month only date field
SELECT
DATEADD(MONTH, DATEDIFF(MONTH, 0, <dateField>), 0) AS [year_month_date_field]
FROM
<your_table>
This gets the number of whole months from a base date (0) and then adds them to that base date. Thus ...
Split function equivalent in T-SQL?
...AR(2048) = 'Mike/John/Miko/Matt'; DECLARE CaracString NVARCHAR(1) = '/'; SELECT * FROM dbo.FnSplitString (VarString, CaracString)
– fernando yevenes
Feb 8 '19 at 15:57
ad...
How do you check what version of SQL Server for a database using TSQL?
...
Try
SELECT @@VERSION
or for SQL Server 2000 and above the following is easier to parse :)
SELECT SERVERPROPERTY('productversion')
, SERVERPROPERTY('productlevel')
, SERVERPROPERTY('edition')
From: http://support....
Is there a way to call a stored procedure with Dapper?
...:
DECLARE @output int
EXEC <some stored proc> @i = @output OUTPUT
SELECT @output AS output1
share
|
improve this answer
|
follow
|
...