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SQL JOIN - WHERE clause vs. ON clause
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They are not the same thing.
Consider these queries:
SELECT *
FROM Orders
LEFT JOIN OrderLines ON OrderLines.OrderID=Orders.ID
WHERE Orders.ID = 12345
and
SELECT *
FROM Orders
LEFT JOIN OrderLines ON OrderLines.OrderID=Orders.ID
AND Orders.ID = 12345
The first will re...
ASP.NET 4.5 has not been registered on the Web server
In my Win 7 development machine, and in order to use SQL Express instance instead of the localDB installed by default. I unchecked "Use IIS Express" in my MVC 4 project properties page (Web tab), then I got the following error:
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Set up DNS based URL forwarding in Amazon Route53 [closed]
...r this guide, I'll use the name "url-redirect-example.vivekmchawla.com".
Select whatever region works best for you. If you don't know, keep the default.
Don't worry about setting up logging. Just click the "Create" button when you're ready.
Step 3: Enable Static Website Hosting and Specify...
importing pyspark in python shell
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Turns out that the pyspark bin is LOADING python and automatically loading the correct library paths. Check out $SPARK_HOME/bin/pyspark :
# Add the PySpark classes to the Python path:
export PYTHONPATH=$SPARK_HOME/python/:$PYTHONPATH
I added this line to my .bashrc file...
Strange SQLAlchemy error message: TypeError: 'dict' object does not support indexing
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This should be the selected answer. It solved the issue in my case.
– Gani Simsek
Feb 20 '17 at 13:11
1
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How do I list the symbols in a .so file
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The standard tool for listing symbols is nm, you can use it simply like this:
nm -gD yourLib.so
If you want to see symbols of a C++ library, add the "-C" option which demangle the symbols (it's far more readable demangled).
nm ...
Node.js/Express.js App Only Works on Port 3000
...a Node.js/Express.js app running on my server that only works on port 3000 and I'm trying to figure out why. Here's what I've found:
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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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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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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[...