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MySQL - SELECT WHERE field IN (subquery) - Extremely slow why?
...
Rewrite the query into this
SELECT st1.*, st2.relevant_field FROM sometable st1
INNER JOIN sometable st2 ON (st1.relevant_field = st2.relevant_field)
GROUP BY st1.id /* list a unique sometable field here*/
HAVING COUNT(*) > 1
I think st2.relevant_field must be in the select, because other...
Why use a prime number in hashCode?
...es by 31 will perform non-optimally. However, I would consider such a hash table implementation poorly designed, given how common 31 as a multiplier is.
– ILMTitan
Aug 31 '10 at 21:42
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SQL set values of one column equal to values of another column in the same table
I have a table with two DATETIME columns.
5 Answers
5
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Create nice column output in python
...to set the columns to a minimum of 20 characters and align text to right.
table_data = [
['a', 'b', 'c'],
['aaaaaaaaaa', 'b', 'c'],
['a', 'bbbbbbbbbb', 'c']
]
for row in table_data:
print("{: >20} {: >20} {: >20}".format(*row))
Output:
a ...
How can bcrypt have built-in salts?
...k. It's meant to prevent an attacker with read-only access to the password table from authenticating. For example, you get a backup tape with the table on it.
– erickson
Aug 6 '14 at 22:38
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How to prevent a jQuery Ajax request from caching in Internet Explorer?
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you can define it like this :
let table = $('.datatable-sales').DataTable({
processing: true,
responsive: true,
serverSide: true,
ajax: {
url: "<?php echo site_url("your url"); ?>",
cache: false,
...
Calling a function within a Class method?
...ults inside the class function? e.g I have a query that selects all from a table and then returns a fetch all result set. Is it possible to loop through that result set inside a classes function? e.g class query{ public function show(){ getResults(); while($stmt->fetchCollumn()){ ECHO RESULTS ...
Add a reference column migration in Rails 4
A user has many uploads. I want to add a column to the uploads table that references the user . What should the migration look like?
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What is the best way to use a HashMap in C++?
...rdered map insert and access is in O(1). It is just another name for a hashtable.
An example with (ordered) std::map:
#include <map>
#include <iostream>
#include <cassert>
int main(int argc, char **argv)
{
std::map<std::string, int> m;
m["hello"] = 23;
// check if ke...
How to check if a stored procedure exists before creating it
...ything after AS:
BEGIN
DECLARE @myvar INT
SELECT *
FROM mytable
WHERE @myvar ...
END
This code does exactly same things a stored proc would do, but is not stored on the database side.
That's much like what is called anonymous procedure in PL/SQL.
Update:
Your question tit...