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Transaction isolation levels relation with locks on table
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I want to understand the lock each transaction isolation takes on the table
For example, you have 3 concurrent processes A, B and C. A starts a transaction, writes data and commit/rollback (depending on results). B just executes a SELECT statement to read data. C reads and updates data. All t...
Setting table row height
...nly does now. anyway this is the solution I found to be best since the way table cells work is to expand to their content. so height in a td is effectively min-height, which in this case is actually what you want
– Simon_Weaver
Aug 3 '14 at 23:21
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Find rows that have the same value on a column in MySQL
In a [member] table, some rows have the same value for the email column.
8 Answers
8...
How to select from subquery using Laravel Query Builder?
...Abc::where(..)->groupBy(..); // Eloquent Builder instance
$count = DB::table( DB::raw("({$sub->toSql()}) as sub") )
->mergeBindings($sub->getQuery()) // you need to get underlying Query Builder
->count();
Mind that you need to merge bindings in correct order. If you have ot...
Best way to strip punctuation from a string
...g.punctuation))
It's performing raw string operations in C with a lookup table - there's not much that will beat that but writing your own C code.
If speed isn't a worry, another option though is:
exclude = set(string.punctuation)
s = ''.join(ch for ch in s if ch not in exclude)
This is faster...
How to do a FULL OUTER JOIN in MySQL?
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For a code SAMPLE transcribed from this SO question you have:
with two tables t1, t2:
SELECT * FROM t1
LEFT JOIN t2 ON t1.id = t2.id
UNION
SELECT * FROM t1
RIGHT JOIN t2 ON t1.id = t2.id
The query above works for special cases where a FULL OUTER JOIN operation would not produce any duplicat...
Get button click inside UITableViewCell
I have a view controller with a table view and a separate nib for the table cell template. The cell template has some buttons. I want to access the button click along with the index of the cell clicked inside the view controller where I have defined the Table view.
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Convert a list of data frames into one data frame
... but in about Sep 2011 a new function rbindlist was introduced in the data.table package version 1.8.2, with a remark that "This does the same as do.call("rbind",l), but much faster". How much faster?
library(rbenchmark)
benchmark(
do.call = do.call("rbind", listOfDataFrames),
plyr_rbind.fill ...
Newline in markdown table?
I have the following cells in a markdown table:
4 Answers
4
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Cleaning `Inf` values from an R dataframe
...,lapply(DT, function(x) replace(x, is.infinite(x),NA)))
Option 2 -- data.table
You could use data.table and set. This avoids some internal copying.
DT <- data.table(dat)
invisible(lapply(names(DT),function(.name) set(DT, which(is.infinite(DT[[.name]])), j = .name,value =NA)))
Or using colum...