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SQL standard to escape column names?
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For MySQL, use back ticks `.
For instance:
SELECT `column`, `column2` FROM `table`
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What is the difference between a pseudo-class and a pseudo-element in CSS?
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The CSS 3 selector recommendation is pretty clear about both, but I'll try to show the differences anyway.
Pseudo-classes
Official description
The pseudo-class concept is introduced to permit selection based on information that l...
Exporting data In SQL Server as INSERT INTO
...something else, see screenshot below this one
2008 R2 or later eg 2012
Select "Types of Data to Script" which can be "Data Only", "Schema and Data" or "Schema Only" - the default).
And then there's a "SSMS Addin" Package on Codeplex (including source) which promises pretty much the same func...
How to select the row with the maximum value in each group
In a dataset with multiple observations for each subject I want to take a subset with only the maximum data value for each record. For example, with a following dataset:
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Gulp command not found after install
I installed gulp(globally) and it looks like it worked because it ran this code:
11 Answers
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sed or awk: delete n lines following a pattern
How would I mix patterns and numeric ranges in sed (or any similar tool - awk for example)? What I want to do is match certain lines in a file, and delete the next n lines before proceeding, and I want to do that as part of a pipeline.
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How to indent a few lines in Markdown markup?
...t of it
If you have control over CSS on the page, you could also use a tag and style it, either inline or with CSS rules.
Either way, markdown is not meant as a tool for layout, it is meant to simplify the process of writing for the web, so if you find yourself stretching its feature set to do what ...
How to delete a row by reference in data.table?
...el.idxs' vs. 'keep.idxs'
keep.idxs <- setdiff(DT[, .I], del.idxs); # select row indexes to keep
cols = names(DT);
DT.subset <- data.table(DT[[1]][keep.idxs]); # this is the subsetted table
setnames(DT.subset, cols[1]);
for (col in cols[2:length(cols)]) {
DT.subset[, (col) := DT[...
How can a Java program get its own process ID?
...ctory.getRuntimeMXBean().getName() looks like the best (closest) solution, and typically includes the PID. It's short, and probably works in every implementation in wide use.
On linux+windows it returns a value like 12345@hostname (12345 being the process id). Beware though that according to the doc...
How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
... 0.0 NaN 0.0
3 0.0 1.0 2.0 3.0
4 NaN 0.0 NaN NaN
If you want to select the rows that have two or more columns with null value, you run the following:
>>> qty_of_nuls = 2
>>> df.iloc[df[(df.isnull().sum(axis=1) >=qty_of_nuls)].index]
0 1 2 3
1 0.0 NaN 0...