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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...
Getting the thread ID from a thread
In C# when debugging threads for example, you can see each thread's ID.
11 Answers
11
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How to find serial number of Android device?
I need to use a unique ID for an Android app and I thought the serial number for the device would be a good candidate. How do I retrieve the serial number of an Android device in my app ?
...
Check if a key exists inside a json object
...bove is the JSON object I'm dealing with. I want to check if the 'merchant_id' key exists. I tried the below code, but it's not working. Any way to achieve it?
...
'id' is a bad variable name in Python
Why is it bad to name a variable id in Python?
9 Answers
9
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Remove duplicate rows in MySQL
...de the IGNORE keyword. Like so:
ALTER IGNORE TABLE jobs
ADD UNIQUE INDEX idx_name (site_id, title, company);
This will drop all the duplicate rows. As an added benefit, future INSERTs that are duplicates will error out. As always, you may want to take a backup before running something like thi...
Overriding id on create in ActiveRecord
Is there any way of overriding a model's id value on create? Something like:
13 Answers
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How to select where ID in Array Rails ActiveRecord without exception
When I have array of ids, like
6 Answers
6
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How to drop column with constraint?
....default_constraints dc
JOIN sys.columns c
ON c.default_object_id = dc.object_id
WHERE
dc.parent_object_id = OBJECT_ID('tbloffers')
AND c.name = N'checkin'
IF @@ROWCOUNT = 0 BREAK
EXEC (@sql)
END
...
How to do this in Laravel, subquery where in
...
Consider this code:
Products::whereIn('id', function($query){
$query->select('paper_type_id')
->from(with(new ProductCategory)->getTable())
->whereIn('category_id', ['223', '15'])
->where('active',...