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Redis strings vs Redis hashes to represent JSON: efficiency?
...
> redis.pipelined{ 10000.times{ |i| redis.me_set( "t:#{i}", txt[rand(50000), 63] ) } }; :done
=> :done
> ap redis.info(:memory)
{
"used_memory" => "1251944",
**"used_memory_human" => "1.19M"**, # ~ 72b per key/value
.....
}
> redis.fl...
MySQL CONCAT returns NULL if any field contain NULL
...nvert the NULL values with empty string by wrapping it in COALESCE
SELECT CONCAT(COALESCE(`affiliate_name`,''),'-',COALESCE(`model`,''),'-',COALESCE(`ip`,''),'-',COALESCE(`os_type`,''),'-',COALESCE(`os_version`,'')) AS device_name
FROM devices
...
Elegant way to combine multiple collections of elements?
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I think you might be looking for LINQ's .Concat()?
var combined = foo.Concat(bar).Concat(foobar).Concat(...);
Alternatively, .Union() will remove duplicate elements.
share
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MySQL and GROUP_CONCAT() maximum length
I'm using GROUP_CONCAT() in a MySQL query to convert multiple rows into a single string.
However, the maximum length of the result of this function is 1024 characters.
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How to concatenate and minify multiple CSS and JavaScript files with Grunt.js (0.3.x)
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concat.js is being included in the concat task's source files public/js/*.js. You could have a task that removes concat.js (if the file exists) before concatenating again, pass an array to explicitly define which files you wa...
Javascript Array Concat not working. Why?
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The concat method doesn't change the original array, you need to reassign it.
if ( ref instanceof Array )
this.refs = this.refs.concat( ref );
else
this.refs.push( ref );
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Can I concatenate multiple MySQL rows into one field?
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You can use GROUP_CONCAT:
SELECT person_id, GROUP_CONCAT(hobbies SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;
As Ludwig stated in his comment, you can add the DISTINCT operator to avoid duplicates:
SELECT person_id, GROUP_CONCAT(D...
MySQL select with CONCAT condition
... query itself.
You can either repeat the expression:
SELECT neededfield, CONCAT(firstname, ' ', lastname) as firstlast
FROM users
WHERE CONCAT(firstname, ' ', lastname) = "Bob Michael Jones"
or wrap the query
SELECT * FROM (
SELECT neededfield, CONCAT(firstname, ' ', lastname) as firstlast
...
.NET List Concat vs AddRange
What is the difference between the AddRange and Concat functions on a generic List? Is one recommended over the other?
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How do I spool to a CSV formatted file using SQLPLUS?
... avoid annoying SQLPLUS output formatting:
set linesize 9999
set pagesize 50000
spool myfile.csv
select x
from
(
select col1||';'||col2||';'||col3||';'||col4||';'||col5||';'||col6||';'||col7||';'||col8||';'||col9||';'||col10||';'||col11||';'||col12||';'||col13||';'||col14||';'||col15||';'||col16||'...