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How to drop columns using Rails migration
What's the syntax for dropping a database table column through a Rails migration?
20 Answers
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Rails: FATAL - Peer authentication failed for user (PG::Error)
...tly by creating a database and assigning ownership to your app's user to establish the connection. To create a new user in postgresql 9 run:
sudo -u postgres psql
set the postgresql user password if you haven't, it's just backslash password.
postgres=# \password
Create a new user and password ...
How to add multiple columns to a table in Postgres?
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Try this :
ALTER TABLE table ADD COLUMN col1 int, ADD COLUMN col2 int;
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Getting “Lock wait timeout exceeded; try restarting transaction” even though I'm not using a transac
... holding a record lock on some record (you're updating every record in the table!) for too long, and your thread is being timed out.
You can see more details of the event by issuing a
SHOW ENGINE INNODB STATUS
after the event (in sql editor). Ideally do this on a quiet test-machine.
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Performance of FOR vs FOREACH in PHP
..._arr1 = array();
$test_arr2 = array();
$test_arr3 = array();
// hash tables
$test_arr4 = array();
$test_arr5 = array();
for ($i = 0; $i < $test_arr_size; ++$i)
{
mt_srand();
$hash = md5(mt_rand());
$key = substr($hash, 0, 5).$i;
$test_arr1[$i] = $test_arr2[$i] = $t...
Child inside parent with min-height: 100% not inheriting height
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Second, the workaround I found:
If I set my container element to display:table with height:inherit it acts exactly the same way as if I'd give it a min-height of 100%. And - more importantly - if I set the child element to display:table-cell it will perfectly inherit the height of the container el...
How to atomically delete keys matching a pattern using Redis
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Lua's unpack transforms a table in a "list of independent variables" (other languages call that explode) but the max number is not dependent on the syste memory; it's fixed in lua through the LUAI_MAXSTACK constant. In Lua 5.1 & LuaJIT it's 8000 a...
CSS to make HTML page footer stay at bottom of the page with a minimum height, but not overlap the p
...w are 4 different methods of mine:
In each example the texts are freely-editable to illustrate how the content would render in different scenarios.
1) Flexbox
body{ height:100vh; margin:0; }
header{ min-height:50px; background:lightcyan; }
footer{ min-height:50px; background:PapayaWhip; }
/* ...
How can I test a Windows DLL file to determine if it is 32 bit or 64 bit? [duplicate]
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Gory details
A DLL uses the PE executable format, and it's not too tricky to read that information out of the file.
See this MSDN article on the PE File Format for an overview. You need to read the MS-DOS header, then read the IMAGE_NT_HEADERS structure. This ...
Remove specific characters from a string in Python
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Strings in Python are immutable (can't be changed). Because of this, the effect of line.replace(...) is just to create a new string, rather than changing the old one. You need to rebind (assign) it to line in order to have that variable take the new...