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SQL join: selecting the last records in a one-to-many relationship
...er id). When we find that to be true, then p1 is the most recent purchase for that customer.
Regarding indexes, I'd create a compound index in purchase over the columns (customer_id, date, id). That may allow the outer join to be done using a covering index. Be sure to test on your platform, bec...
Real life example, when to use OUTER / CROSS APPLY in SQL
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Some uses for APPLY are...
1) Top N per group queries (can be more efficient for some cardinalities)
SELECT pr.name,
pa.name
FROM sys.procedures pr
OUTER APPLY (SELECT TOP 2 *
FROM sys.parameters...
PostgreSQL DISTINCT ON with different ORDER BY
...e to add the address_id to the order by.
Alternatively, if you're looking for the full row that contains the most recent purchased product for each address_id and that result sorted by purchased_at then you're trying to solve a greatest N per group problem which can be solved by the following appro...
When and why I should use session_regenerate_id()?
...lace the current session ID with a new one, and keep the current session information.
What does it do?
It mainly helps prevent session fixation attacks. Session fixation attacks is where a malicious user tries to exploit the vulnerability in a system to fixate (set) the session ID (SID) of another u...
Join/Where with LINQ and Lambda
...in an sql "join" statement)
meta => meta.Post_ID, // Select the foreign key (the second part of the "on" clause)
(post, meta) => new { Post = post, Meta = meta }) // selection
.Where(postAndMeta => postAndMeta.Post.ID == id); // where statement
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Can I bind an array to an IN() condition?
...der using PDO. The use case here is attempting to pass an array of values for use with an IN() condition.
21 Answers
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CodeIgniter activerecord, retrieve last insert id?
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the userguide is your best friend for things like this. i have been using codeigniter for 2+ years and i still find functions like this that i never knew about.
– Tom Schlick
Jan 3 '10 at 10:02
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unique object identifier in javascript
...ed to do some experiment and I need to know some kind of unique identifier for objects in javascript, so I can see if they are the same. I don't want to use equality operators, I need something like the id() function in python.
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Custom toast on Android: a simple example
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toast.setView(layout);
toast.show();
And check out the below links also for a custom Toast.
Custom Toast with Analog Clock
YouTube: Creating Custom Toast With Button in Android Studio
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javascript find and remove object in array based on key value
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I can grep the array for the id, but how can I delete the entire object where id == 88
Simply filter by the opposite predicate:
var data = $.grep(data, function(e){
return e.id != id;
});
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