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When to add what indexes in a table in Rails
...ndex" to the automatically created "id" column?
No, this is already done by rails
Should I add "index(unique)" to the automatically created "id" column?
No, same as above
If I add index to two foreign keys at once (add_index (:users, [:category_id, :state_id]), what happens? How is this ...
How can I assign an ID to a view programmatically?
... an ID to a view like android:id="@+id/something" and then call findViewById() , but when creating a view programmatically, how do I assign an ID?
...
Cannot truncate table because it is being referenced by a FOREIGN KEY constraint?
... cannot check to see whether the records in the table are being referenced by a record in the child table.
This is why DELETE works and TRUNCATE TABLE doesn't: because the database is able to make sure that it isn't being referenced by another record.
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MySQL ON vs USING?
... Actually, both interpret to plain old Theta-style. You can see that by invoking EXPLAIN EXTENDED on your query, followed by SHOW WARNINGS.
– Shlomi Noach
Jul 6 '12 at 17:49
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find vs find_by vs where
... suits your needs best.
The find method is usually used to retrieve a row by ID:
Model.find(1)
It's worth noting that find will throw an exception if the item is not found by the attribute that you supply. Use where (as described below, which will return an empty array if the attribute is not f...
Postgres unique constraint vs index
...ad some doubts about this basic but important issue, so I decided to learn by example.
Let's create test table master with two columns, con_id with unique constraint and ind_id indexed by unique index.
create table master (
con_id integer unique,
ind_id integer
);
create unique index maste...
How can I get the ID of an element using jQuery?
...s a JQuery selector and returns an array() of results not a single element by its default functionality
an alternative for DOM selector in jquery is
$('#test').prop('id')
which is different from .attr() and $('#test').prop('foo') grabs the specified DOM foo property, while $('#test').attr('foo'...
dynamically add and remove view to viewpager
...
After figuring out which ViewPager methods are called by ViewPager and which are for other purposes, I came up with a solution. I present it here since I see a lot of people have struggled with this and I didn't see any other relevant answers.
First, here's my adapter; hopefu...
HTML input - name vs. id [duplicate]
... can see the URL there are workarounds
Is referenced in JS with getElementsByName()
Shares the same namespace as the id attribute
Must begin with a letter
According to specs is case sensitive, but most modern browsers don't seem to follow this
Used on form elements to submit information. Only input ...
API pagination best practices
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(Default sort of foos is by creation date, so row insertion is not a problem.)
– 2arrs2ells
Dec 19 '12 at 22:55
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