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Comparing two dataframes and getting the differences
... behaviour for pd.concat(), here's the docs pandas.pydata.org/pandas-docs/stable/merging.html
– Thanos
Apr 17 '16 at 18:35
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EF Code First foreign key without navigation property
...public override void Up()
{
// other stuff...
AddForeignKey("ChildTableName", "ParentId", "ParentTableName", "Id",
cascadeDelete: true); // or false
CreateIndex("ChildTableName", "ParentId"); // if you want an index
}
Running this migration (update-database on package manage c...
Mac SQLite editor [closed]
... Unless I'm missing something, it doesn't allow you to alter existing tables.
– mahdaeng
Dec 12 '11 at 20:54
1
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How do you get the length of a list in the JSF expression language?
...java.sun.com/jsp/jstl/functions" prefix="fn"%>
<h:outputText value="Table Size = #{fn:length(SystemBean.list)}"/>
On screen it displays the Table size
Example: Table Size = 5
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im...
Cookie overflow in rails application?
...xample.
Here is the steps
Generate a migration that creates the session table
rake db:sessions:create
Run the migration
rake db:migrate
Modify config/initializers/session_store.rb from
(App)::Application.config.session_store :cookie_store, :key => 'xxx'
to
(App)::Application.config.ses...
Are negative array indexes allowed in C?
...want to use negative indexes, I have used them in two contexts:
Having a table of combinatorial numbers that tells you comb[1][-1] = 0; you can always check indexes before accessing the table, but this way the code looks cleaner and executes faster.
Putting a centinel at the beginning of a table. ...
Sqlite LIMIT / OFFSET query
... necessarily mean it's in the order you want. The only way to get a predictable order is to use ORDER BY explicitly.
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Tactics for using PHP in a high-load site
...lize your schemas. This means that rather than to have multiple relational tables, you should instead opt to have one big table. In general, joins are a waste of precious DB resources because doing multiple prepares and collation burns disk I/O's. Avoid them when you can.
The trade-off here is ...
best practice to generate random token for forgot password
...rch in about a week's time for a low-budget attacker:
mt_rand() is predictable (and only adds up to 31 bits of entropy)
uniqid() only adds up to 29 bits of entropy
md5() doesn't add entropy, it just mixes it deterministically
Since a 56-bit DES key can be brute-forced in about 24 hours, and an a...
SQL UPDATE all values in a field with appended string CONCAT not working
...rver 'data' was a keyword. Maybe a less ambiguous example would be: UPDATE table SET column_name=concat(column_name, 'string');
– Kiky Rodriguez
Dec 11 '18 at 19:09
add a comm...