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Is there a performance gain in using single quotes vs double quotes in ruby?
... x.report("assign double") { n.times do; c = "a string"; end}
x.report("concat single") { n.times do; 'a string ' + 'b string'; end}
x.report("concat double") { n.times do; "a string " + "b string"; end}
end
$ ruby benchmark_quotes.rb
user system total r...
Include headers when using SELECT INTO OUTFILE?
... how to get column list of table my_table in my_schema.
-- override GROUP_CONCAT limit of 1024 characters to avoid a truncated result
set session group_concat_max_len = 1000000;
select GROUP_CONCAT(CONCAT("'",COLUMN_NAME,"'"))
from INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'my_table'
AND TABLE...
MySQL DISTINCT on a GROUP_CONCAT()
I am doing SELECT GROUP_CONCAT(categories SEPARATOR ' ') FROM table . Sample data below:
6 Answers
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Why is it Valid to Concatenate Null Strings but not to Call “null.ToString()”?
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The reason for first one working:
From MSDN:
In string concatenation operations,the C# compiler treats a null string the same as an empty string, but it does not convert the value of the original null string.
More information on the + binary operator:
The binary + operator perf...
Union Vs Concat in Linq
I have a question on Union and Concat . I guess both are behaving same in case of List<T> .
3 Answers
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MySQL: Sort GROUP_CONCAT values
In short: Is there any way to sort the values in a GROUP_CONCAT statement?
2 Answers
2...
Oracle SQL, concatenate multiple columns + add text
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You have two options for concatenating strings in Oracle:
CONCAT
Using ||
CONCAT example:
CONCAT(
CONCAT(
CONCAT(
CONCAT(
CONCAT('I like ', t.type_desc_column),
' cake with '),
t.icing_desc_column),
' and ...
MySQL combine two columns into one column
...t start with a digit, then the converted value is 0.
So try this:
select concat(column1, column2)
Two ways to add a space:
select concat(column1, ' ', column2)
select concat_ws(' ', column1, column2)
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Import multiple csv files into pandas and concatenate into one DataFrame
I would like to read several csv files from a directory into pandas and concatenate them into one big DataFrame. I have not been able to figure it out though. Here is what I have so far:
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How do you concatenate Lists in C#?
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Concat returns a new sequence without modifying the original list. Try myList1.AddRange(myList2).
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