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How to add column if not exists on PostgreSQL?
...s, _col text, _type regtype)
RETURNS bool AS
$func$
BEGIN
IF EXISTS (SELECT 1 FROM pg_attribute
WHERE attrelid = _tbl
AND attname = _col
AND NOT attisdropped) THEN
RETURN FALSE;
ELSE
EXECUTE format('ALTER TABLE %s ADD COLUMN %I %s...
How to achieve code folding effects in Emacs?
...on: C-h k C-x $
tells us that the above key combination is calling
set-selective-display, a function that takes one numerical argument
(the M-1 prefix passes 1 as the value of that argument) and,
unsurprisingly, sets the variable selective-display to the value of
that argument.
from mino...
SQL: deleting tables with prefix
...r you:
In the MySQL shell or through PHPMyAdmin, use the following query
SELECT CONCAT( 'DROP TABLE ', GROUP_CONCAT(table_name) , ';' )
AS statement FROM information_schema.tables
WHERE table_name LIKE 'myprefix_%';
This will generate a DROP statement which you can than copy and execut...
Drop data frame columns by name
...op=FALSE to keep R from converting your data frame to a vector if you only select a single column. Don't forget that data frames are lists, so list selection (one-dimensional like I did) works perfectly well and always returns a list. Or a data frame in this case, which is why I prefer to use it.
...
Save PL/pgSQL output from PostgreSQL to a CSV file
...e or automate, you can use Postgresql's built in COPY command. e.g.
Copy (Select * From foo) To '/tmp/test.csv' With CSV DELIMITER ',' HEADER;
This approach runs entirely on the remote server - it can't write to your local PC. It also needs to be run as a Postgres "superuser" (normally called "ro...
LINQ's Distinct() on a particular property
...
(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
HashSet<TKey> seenKeys = new HashSet<TKey>();
foreach (TSource element in source)
{
if (seenKeys.Add(keySelector(element)))
{
yield return element;
}
...
Code Wrap IntelliJ?
...o right click the gutter (the vertical bar where line number is shown) and select "Use Soft wraps" - thanks to Bajal for comment.
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SQL Server Linked Server Example Query
...a Linked Server in SSMS Object Explorer, right-click, and Script Table as, SELECT To, and New Query Editor Window. The resulting SELECT statement will include the correct, fully-qualified path to the table. I had a mystery database qualifier in working with Sybase and this gave me the correct name.
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Saving results with headers in Sql Server Management Studio
...reopen SSMS after changing this option.
On the SQL Editor Toolbar you can select save to file without having to restart SSMS
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fatal error: malformed or corrupted AST file - Xcode
...olved the issue for me. In Xcode, go to Window->Organizer->Projects, select your project, and press the "Delete..." button next to "Derived data".
If this doesn't work, you can try to do a Product->Clean (Cmd+Shift+k).
...