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Difference between “@id/” and “@+id/” in Android
In @+id/ the plus symbol + instructs to create a new resource name and add in to the R.java file but what about @id/ ? From the documentation of ID : when referencing an Android resource ID , you do not need the plus symbol, but must add the android package namespace, like so:
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What is the difference between id and class in CSS, and when should I use them? [duplicate]
Here I gave an id to the div element and it's applying the relevant CSS for it.
15 Answers
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How to reset postgres' primary key sequence when it falls out of sync?
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-- Login to psql and run the following
-- What is the result?
SELECT MAX(id) FROM your_table;
-- Then run...
-- This should be higher than the last result.
SELECT nextval('your_table_id_seq');
-- If it's not higher... run this set the sequence last to your highest id.
-- (wise to run a quick pg...
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...ies 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 doesn't match anythi...
Rails: Why does find(id) raise an exception in rails? [duplicate]
If there is no user with an id of 1 in the database, trying User.find(1) will raise an exception.
2 Answers
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How to get cumulative sum
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select t1.id, t1.SomeNumt, SUM(t2.SomeNumt) as sum
from @t t1
inner join @t t2 on t1.id >= t2.id
group by t1.id, t1.SomeNumt
order by t1.id
SQL Fiddle example
Output
| ID | SOMENUMT | SUM |
-----------------------
| 1 | 1...
PostgreSQL function for last inserted ID
In PostgreSQL, how do I get the last id inserted into a table?
10 Answers
10
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How can I change CSS display none or block property using jQuery?
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The correct way to do this is to use show and hide:
$('#id').hide();
$('#id').show();
An alternate way is to use the jQuery css method:
$("#id").css("display", "none");
$("#id").css("display", "block");
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MYSQL OR vs IN performance
...elieve people who give their "opinion", science is all about testing and evidence.
I ran a loop of 1000x the equivalent queries (for consistency, I used sql_no_cache):
IN: 2.34969592094s
OR: 5.83781504631s
Update:
(I don't have the source code for the original test, as it was 6 years ago, though...
PostgreSQL - fetch the row which has the Max value for a column
...le (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id
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