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Purpose of Trigraph sequences in C++?
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I've seen trigraphs used in the early '90s to help convert PL/1 programs from a mainframe to be run/compiled/debugged on a PC.
They were dabbling with editing PL/I on the PC using a PL/I to C compiler and they wanted the code to work when moved back to the mainframe which ...
Rails raw SQL example
How can I convert this code to raw sql and use in rails? Because When I deploy this code in heroku,there is a request timeout error.I think this will be faster if I use raw sql.
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SQL UPDATE all values in a field with appended string CONCAT not working
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convert the NULL values with empty string by wrapping it in COALESCE
"UPDATE table SET data = CONCAT(COALESCE(`data`,''), 'a')"
OR
Use CONCAT_WS instead:
"UPDATE table SET data = CONCAT_WS(',',data, 'a')"
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str performance in python
...hon code ( python 2.6 up to 3.2 ), I discovered that the
str method to convert an object (in my case an integer) to a string is almost an order of magnitude slower than using string formatting.
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Return value in a Bash function
...5, 0 meaning "success"). So return is not what you want.
You might want to convert your return statement to an echo statement - that way your function output could be captured using $() braces, which seems to be exactly what you want.
Here is an example:
function fun1(){
echo 34
}
function fun2()...
Primary key or Unique index?
At work we have a big database with unique indexes instead of primary keys and all works fine.
15 Answers
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Recursive directory listing in DOS
...ptions offered by FINDSTR. You can also use the excellent unxutils, but it converts the output to UNIX by default, so you no longer get CR+LF; FINDSTR offers the best Windows option.
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MySQL - Rows to Columns
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I'm going to add a somewhat longer and more detailed explanation of the steps to take to solve this problem. I apologize if it's too long.
I'll start out with the base you've given and use it to define a couple of terms that I'll use for the rest of this p...
Multiple Updates in MySQL
... id. if the site has new records then i will end up inserting only the ids and count except all other information. if and only if there is an entry for the id then it should update else it should skip. what shall i do?
– Jayapal Chandran
Aug 30 '10 at 13:30
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How can I generate an ObjectId with mongoose?
...nerate a new new ObjectId
const newId2 = new mongoose.Types.ObjectId();
// Convert string to ObjectId
const newId = new mongoose.Types.ObjectId('56cb91bdc3464f14678934ca');
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