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difference between primary key and unique key
...ey, unique key, etc are collectively called as Candidate Key.
However, DBA selected a key from candidate key for searching records is called Primary key.
Difference between Primary Key and Unique key
1. Behavior: Primary Key is used to identify a row (record) in a table, whereas Unique-key is to...
IntelliJ beginning of file keyboard shortcut
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To select a block quickly: SHIFT-FN-CMD + UP/DOWN ARROW KEYS .. this solution got me on the right path - thanks!
– Gene Bo
Apr 14 '15 at 19:05
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How do I use itertools.groupby()?
...string)]
will give you a list of 2-tuples where the first element is the char and the 2nd is the number of repetitions.
Edit: Note that this is what separates itertools.groupby from the SQL GROUP BY semantics: itertools doesn't (and in general can't) sort the iterator in advance, so groups with t...
In Eclipse, what can cause Package Explorer “red-x” error-icon when all Java sources compile without
...ers e.g __duplicatefile.java . To fix this, rightclick on the project and select : Show In > Navigator . Then delete the duplicate files with underscore and build your project.
– GraSim
May 29 '15 at 10:28
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Replacing column values in a pandas DataFrame
...a column (the second 'female' in your w['female']['female']) doesn't mean "select rows where the value is 'female'". It means to select rows where the index is 'female', of which there may not be any in your DataFrame.
shar...
how to stop browser back button using javascript
...me because window.location.hash should always return the hash with the '#' character and _hash will never contains the '#' caracter. Do you recall anything on that ? Is that just a protection in case the browser does not return the '#' char in location.hash ?
– baraber
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CreateProcess error=206, The filename or extension is too long when running main() method
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In intellij there is an option to 'shorten command line', select 'JAR manifest' or '@argFiles' would solve the problem, basically it will put your lengthy class path into a jar file or a temp file
share
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#1071 - Specified key was too long; max key length is 1000 bytes
... the best prefix length for a given column? Here's a method to find out:
SELECT
ROUND(SUM(LENGTH(`menu_link`)<10)*100/COUNT(`menu_link`),2) AS pct_length_10,
ROUND(SUM(LENGTH(`menu_link`)<20)*100/COUNT(`menu_link`),2) AS pct_length_20,
ROUND(SUM(LENGTH(`menu_link`)<50)*100/COUNT(`menu_...
How do I change db schema to dbo
...which will generate a set of ALTER sCHEMA statements for all your talbes:
SELECT 'ALTER SCHEMA dbo TRANSFER ' + TABLE_SCHEMA + '.' + TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'jonathan'
You then have to copy and run the statements in query analyzer.
Here's an older script t...
How to write an XPath query to match two attributes?
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//div[@id='..' and @class='...]
should do the trick. That's selecting the div operators that have both attributes of the required value.
It's worth using one of the online XPath testbeds to try stuff out.
sha...