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What is the optimal length for user password salt? [closed]
...ices for how long the salt should be? I'll be storing the salt in my user table, so I would like the best tradeoff between storage size and security. Is a random 10 character salt enough? Or do I need something longer?
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How to change column datatype from character to numeric in PostgreSQL 8.4
...rom old to new type.
So this might work (depending on your data):
alter table presales alter column code type numeric(10,0) using code::numeric;
-- Or if you prefer standard casting...
alter table presales alter column code type numeric(10,0) using cast(code as numeric);
This will fail if you h...
How to get cumulative sum
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@Franklin Only cost efficient for small tables. Cost grows proportional to the square of the number of rows. SQL Server 2012 allows this to be done much more efficiently.
– Martin Smith
May 18 '13 at 19:57
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How to save a data.frame in R?
...ta.Rda")
Then load it with:
load("data.Rda")
You could also use write.table() or something like that to save the table in plain text, or dput() to obtain R code to reproduce the table.
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Replace all 0 values to NA
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What would the equivalent syntax be for a data.table object?
– itpetersen
Dec 7 '14 at 5:33
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Laravel Eloquent groupBy() AND also return count of each group
I have a table that contains, amongst other columns, a column of browser versions. And I simply want to know from the record-set, how many of each type of browser there are. So, I need to end up with something like this: Total Records: 10; Internet Explorer 8: 2; Chrome 25: 4; Firefox 20: 4. (All ad...
Is there a way to view past mysql queries with phpmyadmin?
I'm trying to track down a bug that's deleting rows in a mysql table.
13 Answers
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Entity Framework: One Database, Multiple DbContexts. Is this a bad idea? [closed]
...ngle context per app can be expensive if the application has many entities/tables. Thus depending on the schema, it might also make sense to have multiple contexts.
– DarthVader
May 13 '13 at 7:04
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select * vs select column
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It always pulls a tuple (except in cases where the table has been vertically segmented - broken up into columns pieces), so, to answer the question you asked, it doesn't matter from a performance perspective. However, for many other reasons, (below) you should always select ...
How to implement a Map with multiple keys? [duplicate]
...nother solution is to use Google's Guava
import com.google.common.collect.Table;
import com.google.common.collect.HashBasedTable;
Table<String, String, Integer> table = HashBasedTable.create();
The usage is really simple:
String row = "a";
String column = "b";
int value = 1;
if (!table.c...