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postgresql return 0 if returned value is null
...ns the first of its arguments that is not null.
Null is returned only if all arguments are null. It is often
used to substitute a default value for null values when data is
retrieved for display.
Edit
Here's an example of COALESCE with your query:
SELECT AVG( price )
FROM(
SELECT *, cum...
Cross cutting concern example
...ently used in distributed applications to aid debugging by tracing method calls. Suppose we do logging at both the beginning and the end of each function body. This will result in crosscutting all classes that have at least one function.
(Courtesy)
...
Filter git diff by type of change
...de) changed
U Unmerged
X Unknown
B have had their pairing Broken
* All-or-none
Any combination of the filter characters may be used.
When * (All-or-none) is added to the combination, all paths are
selected if there is any file that matches other criteria in the
comparison; ...
innerText vs innerHTML vs label vs text vs textContent vs outerText
... a couple of differences:
Note that while textContent gets the content of all elements, including <script> and <style> elements, the mostly equivalent IE-specific property, innerText, does not.
innerText is also aware of style and will not return the text of hidden elements, whereas te...
How to remove an element from a list by index
...org/projects/python/trunk/Objects/listobject.c how PyList_GetItem() essentially returns ((PyListObject *)op) -> ob_item[i]; - the ith element of an array.
– glglgl
Sep 9 '13 at 7:53
...
JPA or JDBC, how are they different?
...sh for the same. I saw some examples and also read the Oracle docs to know all about Java EE 5. Connecting to a database was very simple. I opened a dynamic web project, created a session EJB , I used EntityManager and with the get methods could access the stored data table.
...
Redis strings vs Redis hashes to represent JSON: efficiency?
I want to store a JSON payload into redis. There's really 2 ways I can do this:
3 Answers
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what's the difference between “hadoop fs” shell commands and “hdfs dfs” shell commands?
...s dfs instead.
hdfs dfs <args>
same as 2nd i.e would work for all the operations related to HDFS and is the recommended command instead of hadoop dfs
below is the list categorized as hdfs commands.
namenode|secondarynamenode|datanode|dfs|dfsadmin|fsck|balancer|fetchdt|oiv|dfsgroups
...
Why is using 'eval' a bad practice?
...d eval have nothing to do with each other. An application that's fundamentally mis-designed is fundamentally mis-designed. eval is no more the root cause of bad design than division by zero or attempting to import a module which is known not to exist. eval isn't insecure. Applications are insecu...
What is eager loading?
...hing when asked. Classic example is when you multiply two matrices. You do all the calculations. That's eager loading;
Lazy loading: you only do a calculation when required. In the previous example, you don't do any calculations until you access an element of the result matrix; and
Over-eager loadin...