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How does Spring autowire by name when more than one matching bean is found?
...es, it is often necessary to have more control over the selection process. One way to accomplish this is with Spring's @Qualifier annotation. This allows for associating qualifier values with specific arguments, narrowing the set of type matches so that a specific bean is chosen for each argument. I...
What exactly is a Maven Snapshot and why do we need it?
I am a bit confused about the meaning of a Maven Snapshot and why we build one?
13 Answers
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Is #pragma once a safe include guard?
...eason not to use a standard #ifndef include guard. It works just fine. The one caveat is that GCC didn't support #pragma once before version 3.4.
I also found that, at least on GCC, it recognizes the standard #ifndef include guard and optimizes it, so it shouldn't be much slower than #pragma once.
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Insert into … values ( SELECT … FROM … )
...ondition changed to table2.country and returns number of rows greater than one? I got similar issue here: stackoverflow.com/questions/36030370/…
– vijayrana
Mar 17 '16 at 6:25
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What is the purpose of std::make_pair vs the constructor of std::pair?
...//www.cplusplus.com/reference/std/utility/make_pair/
pair <int,int> one;
pair <int,int> two;
one = make_pair (10,20);
two = make_pair (10.5,'A'); // ok: implicit conversion from pair<double,char>
Aside from the implicit conversion bonus of it, if you didn't use make_pair you'd ...
How can you represent inheritance in a database?
...table as in your first option is probably the simplest design. As you mentioned, many attributes that are subtype-specific will have to be given a NULL value on rows where these attributes do not apply. With this model, you would have one policies table, which would look something like this:
+------...
PostgreSQL - fetch the row which has the Max value for a column
... vary in production based on actual machine load/data access spread. When one query appears slightly faster (<20%) than the other but has a much higher cost, it will generally be wiser to choose the one with higher execution time but lower cost.
When you expect that there will be no competition...
What is the difference between Cloud, Grid and Cluster? [closed]
... essentially smashing up many machines to make a really big & powerful one. This is a much more difficult architecture than cloud or grid to get right because you have to orchestrate all nodes to work together, and provide consistency of things such as cache, memory, and not to mention clocks. O...
How do I create an empty array/matrix in NumPy?
...mally use a list. I want to create an empty array (or matrix) and then add one column (or row) to it at a time.
13 Answers
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Want to find records with no associated records in Rails
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This is still pretty close to SQL, but it should get everyone with no friends in the first case:
Person.where('id NOT IN (SELECT DISTINCT(person_id) FROM friends)')
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