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Oracle 分组后取每组第一条数据 - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...LECT *
FROM (SELECT ROW_NUMBER() OVER(PARTITION BY T.field1, T.field2 ORDER BY T.field3 DESC) rowNo, T.*
FROM table_xxx T)
WHERE rowNo = 1;
oracle group ROW_NUMBER
'and' (boolean) vs '&' (bitwise) - Why difference in behavior with lists vs numpy arrays?
...ting. I hadn't thought of it that way. I was thinking of {a,b} as being an ordered pair (even though you used set brackets), because I was thinking you meant to try: (True, True), (True, False), (False, True), and (False, False), so I thought (True, True) is not a subset of {True, False}, but I can ...
onActivityResult() & onResume() [duplicate]
...e Hackborn explains that onActivityResult() is called before onResume() in order to allow anything that might affect the UI to be received and available prior to updating the UI (presumably to avoid a double-update - once in onResume() without the returned result, and then in onActivityResult(), add...
Why does X[Y] join of data.tables not allow a full outer join, or a left join?
...n of X[Y]
le <- Y[X]
mallx <- merge(X, Y, all.x = T)
# the column order is different so change to be the same as `merge`
setcolorder(le, names(mallx))
identical(le, mallx)
# [1] TRUE
If you want a full outer join
# the unique values for the keys over both data sets
unique_keys <- uniq...
What is a stack trace, and how can I use it to debug my application errors?
...if(dog == null || dog.firstName == null) return;
The above is the proper order to check for nulls, we start with the base object, dog in this case, and then begin walking down the tree of possibilities to make sure everything is valid before processing. If the order were reversed a NPE could pote...
What optimizations can GHC be expected to perform reliably?
... also explains the passes fairly well. This page explains the optimization ordering, though, like the majority of the Trac Wiki, it is out of date.
For specifics, the best thing to do is probably to look at how a specific program is compiled. The best way to see which optimizations are being perfor...
How serious is this new ASP.NET security vulnerability and how can I workaround it?
...e information about the way that the site's decryption process works.
In order for the attack to work the following must be true:
Your application must give an error message about the padding being invalid.
Someone must tamper with your encrypted cookies or viewstate
So, if you return human re...
Why do I get TypeError: can't multiply sequence by non-int of type 'float'?
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www-data permissions?
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How to best position Swing GUIs?
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