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How do you manually execute SQL commands in Ruby On Rails using NuoDB
...n.execute("foo")
with "foo" being the sql statement( i.e. "SELECT * FROM table").
This command will return a set of values as a hash and put them into the results variable.
So on my rails application_controller.rb I added this:
def execute_statement(sql)
results = ActiveRecord::Base.connectio...
Subset of rows containing NA (missing) values in a chosen column of a data frame
...t "NA" strings to NA values, and let "NULL" strings as is).
If using read.table() or read.csv(), you should consider the "na.strings" argument to do clean data import, and always work with real R NA values.
An example, working in both cases "NULL" and "NA" cells :
DF <- read.csv("file.csv", na...
Is it a good idea to index datetime field in mysql?
.... In my application I will have many rows for example I currently have one table with 4 million records. Most of my queries use datetime clause to select data. Is it a good idea to index datetime fields in mysql database?
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What is the difference between Non-Repeatable Read and Phantom Read?
What is the difference between non-repeatable read and phantom read?
9 Answers
9
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What is the best place for storing uploaded images, SQL database or disk file system? [closed]
...ll consume a lot of memory. Also, if you use a storage engine that employs table-locks for writes (ISAM for example), your files table might be locked often depending on the size / rate of files you are storing there.
Regarding security - I usually store the files in a directory that is outside of...
Rails new vs create
...fferently.
An HTTP GET to /resources/new is intended to render a form suitable for creating a new resource, which it does by calling the new action within the controller, which creates a new unsaved record and renders the form.
An HTTP POST to /resources takes the record created as part of the ne...
SET NAMES utf8 in MySQL?
...ters to show on websites properly when the data was queried from MySQL. My tables and columns are set to UTF-8 in MySQL—so should this be necessary?
– NexusRex
Aug 30 '11 at 19:15
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Select something that has more/less than x character
...L Server, Use the LEN (Length) function:
SELECT EmployeeName FROM EmployeeTable WHERE LEN(EmployeeName) > 4
MSDN for it states:
Returns the number of characters of the specified string expression,
excluding trailing blanks.
Here's the link to the MSDN
For oracle/plsql you can use Leng...
ERROR: permission denied for sequence cities_id_seq using Postgres
...
Interesting. I did a GRANT all on the table that my sequence is in, but this doesn't seem to cover the sequence. This also seems to very by OS.
– Kinnard Hockenhull
Jun 7 '14 at 15:48
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Should try…catch go inside or outside a loop?
...ch structures are placed. Internally, they are implemented as a code-range table in a structure that is created when the method is called. While the method is executing, the try/catch structures are completely out of the picture unless a throw occurs, then the location of the error is compared again...