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Using group by on multiple columns
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Group By X means put all those with the same value for X in the one group.
Group By X, Y means put all those with the same values for both X and Y in the one group.
To illustrate using an example, let's say we have the following table, to do with who is attending what subject at a univers...
Is it safe to get values from a java.util.HashMap from multiple threads (no modification)?
... AtomicX classes
Initialize the value into a final field (JLS 17.5).
The ones most interesting for your scenario are (2), (3) and (4). In particular, (3) applies directly to the code I have above: if you transform the declaration of MAP to:
public static volatile HashMap<Object, Object> MAP...
Java synchronized method lock on object, or method?
...object would block each other anyway.
If you want to synchronize only on one variable at a time, so two threads won't block each other while accessing different variables, you have synchronize on them separately in synchronized () blocks. If a and b were object references you would use:
public vo...
How to delete large data of table in SQL without log?
...able with same schema and import these rows back into this ex-Large table.
One last option I can think of is to change your database's Recovery Mode to SIMPLE and then delete rows in smaller batches using a while loop something like this..
DECLARE @Deleted_Rows INT;
SET @Deleted_Rows = 1;
WHILE (...
nginx - client_max_body_size has no effect
...stions from nembleton & rjha94)
I thought it might be helpful for someone, if I added a little clarification to their suggestions. For starters, please be certain you have included your increased upload directive in ALL THREE separate definition blocks (server, location & http). Each shou...
querySelector and querySelectorAll vs getElementsByClassName and getElementById in JavaScript
...r to browser (and from version to version). I'd assume that selector based ones were more expensive (but not in a way that will ever likely to be significant)
– Quentin
Jan 17 '13 at 11:18
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Difference between .on('click') vs .click()
... a single handler for all elements that match your selector, including the ones created dynamically.
...another reason to use .on
As Adrien commented below, another reason to use .on is namespaced events.
If you add a handler with .on("click", handler) you normally remove it with .off("click",...
How to check if one DateTime is greater than the other in C#
...ndDate . I want to make sure StartDate is before EndDate . How is this done in C#?
11 Answers
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Why are these constructs using pre and post-increment undefined behavior?
...lem, there is no "should" involved. If the undefined behavior changes when one of the involved variables is declared volatile, that doesn't prove or change anything. It is undefined; you cannot reason about the behavior.
Your most interesting-looking example, the one with
u = (u++);
is a text-bo...
Markdown: continue numbered list
...bered block. If you leave 2 blank lines, it restarts numbering; leave only one and it continues.
– Rhubarb
Aug 21 '19 at 10:28
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