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difference between primary key and unique key
... there are so many physical entities (such as people, resources, machines, etc.) and virtual entities (their Tasks, transactions, activities).
Typically, business needs to record and process information of those business entities.
These business entities are identified within a whole business doma...
Installing older version of R package
...kage by using R CMD INSTALL on the command line (Terminal, Command Prompt, etc.) once you have the package source ("tarball") locally on your machine, for example using wget (if you have it):
wget http://cran.r-project.org/src/contrib/Archive/ggplot2/ggplot2_0.9.1.tar.gz
or, if you're on Windows,...
What's the best way to store a group of constants that my program uses? [closed]
... various constants that my program uses... string 's, int 's, double 's, etc... What is the best way to store them? I don't think I want an Enum , because the data is not all the same type, and I want to manually set each value. Should I just store them all in an empty class? Or is there a better...
Why and when to use Node.js? [duplicate]
... my ignorance, but imho, when building large scale servers (for say games, etc) you lose FAR too much in strongly typed, OO, compiled languages.
– Demian Brecht
Apr 11 '11 at 17:55
...
What's the hardest or most misunderstood aspect of LINQ? [closed]
...alize that many LINQ extension methods such as Single(), SingleOrDefault() etc have overloads that take lambdas.
You can do :
Single(x => x.id == id)
and don't need to say this - which some bad tutorial got me in the habit of doing
Where(x => x.id == id).Single()
...
connecting to MySQL from the command line
... thank you, 2 questions 1) do you have to include the "- u" "- p" etc, or are those replaced by the username etc 2) if there's no database created do you just leave that blank?
– Leahcim
Feb 27 '11 at 7:13
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Java's Virtual Machine and CLR
...popping those operands off the stack whenever an instruction (add, divide, etc) needs to consume those operands. Each instruction pushes its results back onto the stack.
It's a convenient way to implement a virtual machine, because pretty much every CPU in the world has a stack, but the number of r...
Hibernate vs JPA vs JDO - pros and cons of each? [closed]
... datasources, db4o, hbase, ldap, bigtable, couchdb (plugins for cassandra) etc.
you can easily switch from an sql to non-sql datasource and vice-versa.
no proxy objects and therefore less pain with regards to hashcode() and equals() implementations
more POJO and hence less workarounds required
suppo...
Oracle TNS names not showing when adding new connection to SQL Developer
...tnsnames.ora
$TNS_ADMIN/tnsnames.ora
TNS_ADMIN lookup key in the registry
/etc/tnsnames.ora ( non-windows )
$ORACLE_HOME/network/admin/tnsnames.ora
LocalMachine\SOFTWARE\ORACLE\ORACLE_HOME_KEY
LocalMachine\SOFTWARE\ORACLE\ORACLE_HOME
To see which one SQL Developer is using, issue the command show ...
Set default CRAN mirror permanent in R
...tilde expansion). If this variable is
unset, the default is R_HOME/etc/Rprofile.site, which is used if
it exists (which it does not in a 'factory-fresh' installation).
So do Sys.getenv("R_PROFILE") for the first option, or Sys.getenv("R_HOME") or R.home() for the second option. On m...