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RVM is not a function, selecting rubies with 'rvm use …' will not work
...access to rvm function. If you are running Ubuntu, you can:
Open console
Select Edit -> Profile Preferences
Select tab: Title and Command
Check box 'Run command as a login shell'
Restart terminal
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How to check if PHP array is associative or sequential?
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@ARW "PHP seems to cast everything to an int in an array definition if it can." - yep, that's exactly what happens. The biggest WTF is that it even does this to floats; if you try var_dump([1.2 => 'foo', 1.5 => 'bar']); you'll discover th...
What is the difference between char s[] and char *s?
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static char __unnamed[] = "abc";
char *c = __unnamed;
Note the implicit cast from char[] to char *, which is always legal.
Then if you modify c[0], you also modify __unnamed, which is UB.
This is documented at 6.4.5 "String literals":
5 In translation phase 7, a byte or code of value zero i...
PostgreSQL - max number of parameters in “IN” clause?
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explain select * from test where id in (values (1), (2));
QUERY PLAN
Seq Scan on test (cost=0.00..1.38 rows=2 width=208)
Filter: (id = ANY ('{1,2}'::bigint[]))
But if try 2nd query:
explain select * from test where id = an...
postgresql COUNT(DISTINCT …) very slow
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You can use this:
SELECT COUNT(*) FROM (SELECT DISTINCT column_name FROM table_name) AS temp;
This is much faster than:
COUNT(DISTINCT column_name)
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Java's Virtual Machine and CLR
... uses the same implementation as a List<Object>, with different type-casts at the API boundaries), but each value-type uses its own unique implementation (List<int> generates completely different code from List<double>).
In Java, generic types are a purely a compiler trick. The JV...
Difference between natural join and inner join
...+----------+
The INNER JOIN of TableA and TableB on Column1 will return
SELECT * FROM TableA AS a INNER JOIN TableB AS b USING (Column1);
SELECT * FROM TableA AS a INNER JOIN TableB AS b ON a.Column1 = b.Column1;
+------------+-----------+---------------------+
| a.Column1 | a.Column2 | ...
Rails raw SQL example
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You can do this:
sql = "Select * from ... your sql query here"
records_array = ActiveRecord::Base.connection.execute(sql)
records_array would then be the result of your sql query in an array which you can iterate through.
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How do I calculate tables size in Oracle
...BLE_NAME FORMAT A32
COLUMN OBJECT_NAME FORMAT A32
COLUMN OWNER FORMAT A10
SELECT
owner,
table_name,
TRUNC(sum(bytes)/1024/1024) Meg,
ROUND( ratio_to_report( sum(bytes) ) over () * 100) Percent
FROM
(SELECT segment_name table_name, owner, bytes
FROM dba_segments
WHERE segment_type IN...
jquery how to empty input field
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On a related note, .val([]) can also unselect any selected option in select list... not so much with .val(''). Best thing about it is it's cross-browser support. P.S: This is an alternative to only other efficient cross-browser solution - $("select option").prop("...