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Do I need to create indexes on foreign keys on Oracle?
...A and a table B . A has a foreign key to B on B 's primary key, B_ID .
7 Answers
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How to find out what group a given user has?
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This one shows the user's uid as well as all the groups (with their gids) they belong to
id userid
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What's the difference between session.Merge and session.SaveOrUpdate?
...n, do nothing
if another object associated with the session has the same identifier,
throw an exception
if the object has no identifier property, save() it
if the object's identifier has the value assigned to a newly
instantiated object, save() it
if the object is versioned (by a <v...
How to display unique records from a has_many through relationship?
...te that -> {uniq} in this sense is just an alias for -> {distinct} apidock.com/rails/v4.1.8/ActiveRecord/QueryMethods/uniq It occurs in SQL not ruby
– engineerDave
Mar 26 '15 at 21:37
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Find rows that have the same value on a column in MySQL
...rflow.com/questions/41359879/…
– Syed Asad Abbas Zaidi
Dec 28 '16 at 11:01
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What is the difference between Serializable and Externalizable in Java?
...em. To handle this situation, the java.io.Externalizable interface was provided, which is like java.io.Serializable but with custom-written mechanisms to perform the marshalling and unmarshalling functions (you need to implement readExternal and writeExternal methods on your class). This gives you t...
When to use Comparable and Comparator
.../2627608 There is Version class that uses ComparableVersion. Version - provides with factory methods ComparableVersion supposed to be object (with no static methods) - provides an version that is able to be compare with another one. Responsibilities are separated.
– ses
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Generating a random & unique 8 character string using MySQL
...yVolk's or @GordonLinoff's approach, but with a seeded RAND:
e.g. Assumin id is an AUTO_INCREMENT column:
INSERT INTO vehicles VALUES (blah); -- leaving out the number plate
SELECT @lid:=LAST_INSERT_ID();
UPDATE vehicles SET numberplate=concat(
substring('ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789', ...
Push Notifications in Android Platform
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Google's official answer is the Android Cloud to Device Messaging Framework (deprecated) Google Cloud Messaging(deprecated) Firebase Cloud Messaging
It will work on Android >= 2.2 (on phones that have the Play Store).
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How to get the class of the clicked element?
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"class" is not a valid variable name.
– Fred Bergman
Oct 20 '09 at 9:17
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