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Programmatically selecting text in an input field on iOS devices (mobile Safari)
How do you programmatically select the text of an input field on iOS devices, e.g. iPhone, iPad running mobile Safari?
10 A...
Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc
I've heard that SELECT * is generally bad practice to use when writing SQL commands because it is more efficient to SELECT columns you specifically need.
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PostgreSQL DISTINCT ON with different ORDER BY
...llowing approaches:
The general solution that should work in most DBMSs:
SELECT t1.* FROM purchases t1
JOIN (
SELECT address_id, max(purchased_at) max_purchased_at
FROM purchases
WHERE product_id = 1
GROUP BY address_id
) t2
ON t1.address_id = t2.address_id AND t1.purchased_at = t2...
Sublime Text 2 multiple line edit
...t and edit all lines at once.
It's also called "Split into Lines" in the "Selection" menu.
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COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...for all your queries that need to count everything, even for joins, use *
SELECT boss.boss_id, COUNT(subordinate.*)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
But don't use COUNT(*) for LEFT joins, as that will return 1 even if the subordinate table doe...
Caveats of select/poll vs. epoll reactors in Twisted
...o based apps ) leads me to believe that ePoll is a natural replacement for Select and Poll based networking, especially with Twisted. Which makes me paranoid, its pretty rare for a better technique or methodology not to come with a price.
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Fastest check if row exists in PostgreSQL
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Use the EXISTS key word for TRUE / FALSE return:
select exists(select 1 from contact where id=12)
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How do I find duplicate values in a table in Oracle?
...then use a HAVING clause to find values that appear greater than one time.
SELECT column_name, COUNT(column_name)
FROM table_name
GROUP BY column_name
HAVING COUNT(column_name) > 1;
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What are the differences between poll and select?
I am referring to the POSIX standard select and poll system C API calls.
3 Answers
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Get record counts for all tables in MySQL database
...get the count of rows in all tables in a MySQL database without running a SELECT count() on each table?
19 Answers
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