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mkdir -p functionality in Python [duplicate]
...rs will fail, in all multitasking operating systems. It's like saying "256 chars should be enough for any path created".
– tzot
Mar 2 '09 at 23:42
4
...
Is there a better way to dynamically build an SQL WHERE clause than by using 1=1 at its beginning?
... {2}", clause, appender, condition);
}
Use it like this
string query = "SELECT * FROM Table1 {0}";
string whereClause = string.Empty;
if (condition 1)
whereClause = AddCondition(whereClause, "AND", "Col=1");
if (condition 2)
whereClause = AddCondition(whereClause, "AND", "Col2=2");
str...
Find the number of columns in a table
...
SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_catalog = 'database_name' -- the database
AND table_name = 'table_name'
share
...
Only read selected columns
...from the data.table-package:
You can specify the desired columns with the select parameter from fread from the data.table package. You can specify the columns with a vector of column names or column numbers.
For the example dataset:
library(data.table)
dat <- fread("data.txt", select = c("Year...
How to get ID of the last updated row in MySQL?
...)
SET @update_id := 0;
UPDATE some_table SET column_name = 'value', id = (SELECT @update_id := id)
WHERE some_other_column = 'blah' LIMIT 1;
SELECT @update_id;
EDIT by aefxx
This technique can be further expanded to retrieve the ID of every row affected by an update statement:
SET @uids := nul...
How to list active / open connections in Oracle?
...
Error starting at line 1 in command: select * from FROM v$session Error at Command Line:1 Column:14 Error report: SQL Error: ORA-00903: invalid table name 00903. 00000 - "invalid table name" *Cause: *Action:
– pistacchio
...
How to throw an exception in C?
...);
}catch(int64_t x){
printf("good %ld",x);
}
}
int main(int argc, char *argv[])
{
foo();
return 0;
}
to compile it
gcc -o bar.o -c bar.c && g++ a.cc bar.o && ./a.out
output
good 1976
http://mentorembedded.github.io/cxx-abi/abi-eh.html has more detail info about _...
What is the dual table in Oracle?
...
It's a sort of dummy table with a single record used for selecting when you're not actually interested in the data, but instead want the results of some system function in a select statement:
e.g. select sysdate from dual;
See http://www.adp-gmbh.ch/ora/misc/dual.html
...
Optimal way to concatenate/aggregate strings
...Transact SQL, which should work fine in Azure.
;WITH Partitioned AS
(
SELECT
ID,
Name,
ROW_NUMBER() OVER (PARTITION BY ID ORDER BY Name) AS NameNumber,
COUNT(*) OVER (PARTITION BY ID) AS NameCount
FROM dbo.SourceTable
),
Concatenated AS
(
SELECT
...
Group by in LINQ
... p in persons
group p.car by p.PersonId into g
select new { PersonId = g.Key, Cars = g.ToList() };
Or as a non-query expression:
var results = persons.GroupBy(
p => p.PersonId,
p => p.car,
(key, g) => new { PersonId = key, Cars = g.ToList() });
...