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How to use GROUP BY to concatenate strings in MySQL?
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SELECT id, GROUP_CONCAT(name SEPARATOR ' ') FROM table GROUP BY id;
http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
From the link above, GROUP_CONCAT: This function returns a string res...
What is “rvalue reference for *this”?
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If a class instance is not const, overload resolution will preferentially select the non-const version. If the instance is const, the user can only call the const version. And the this pointer is a const pointer, so the instance cannot be changed.
What "r-value reference for this` does is allow yo...
Quickly reading very large tables as dataframes
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# sqldf as on SO
f <- file("test.csv")
system.time(SQLf <- sqldf("select * from f", dbname = tempfile(), file.format = list(header = T, row.names = F)))
## user system elapsed
## 10.21 0.47 10.73
ff / ffdf
require(ff)
system.time(FFDF <- read.csv.ffdf(file="test.csv",nro...
Disabling Chrome cache for website development
...ck (or hold left click) on the reload button at the top of the browser and select "Empty Cache and Hard Reload."
This will go beyond "Hard Reload" to empty the cache entirely, ensuring that anything downloaded via javascript or etc. will also avoid using the cache. You don't have to mess with set...
How do I put double quotes in a string in vba?
...ring
Dim objDataObj As Object
'\Check that single cell is selected!
If Selection.Cells.Count > 1 Then
MsgBox "Select single cell only!", vbCritical
Exit Sub
End If
'Check if we are not on a blank cell!
If Len(ActiveCell.Formu...
Number of rows affected by an UPDATE in PL/SQL
... block, this can be achieved.
... If anyone has a solution to use it in a SELECT Command, I would be interested.
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Is there a way to loop through a table variable in TSQL without using a cursor?
...impler code.
Depending on your data it may be possible to loop using just SELECT statements as shown below:
Declare @Id int
While (Select Count(*) From ATable Where Processed = 0) > 0
Begin
Select Top 1 @Id = Id From ATable Where Processed = 0
--Do some processing here
Update ATa...
Unique random string generation
...ncat(
Enumerable
.Repeat(0, int.MaxValue)
.Select(e => RandomByte())
.Where(randomByte => randomByte < outOfRange)
.Take(length)
.Select(randomByte => alphabet[randomByte % alphabet.Length])
);
}
byte RandomByte()
{...
How to check Oracle database for long running queries
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This one shows SQL that is currently "ACTIVE":-
select S.USERNAME, s.sid, s.osuser, t.sql_id, sql_text
from v$sqltext_with_newlines t,V$SESSION s
where t.address =s.sql_address
and t.hash_value = s.sql_hash_value
and s.status = 'ACTIVE'
and s.username <> 'SYSTEM'
ord...
What exactly is nullptr?
...rloading a function for both pointers and integers, and passing nullptr to select the pointer version. Passing NULL or 0 would confusingly select the int version.
A cast of nullptr_t to an integral type needs a reinterpret_cast, and has the same semantics as a cast of (void*)0 to an integral type (...