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How do I make a list of data frames?
... data import function for read.csv as appropriate. readr::read_csv or data.table::fread will be faster, or you may also need a different function for a different file type.
Either way, it's handy to name the list elements to match the files
names(my_data) <- gsub("\\.csv$", "", my_files)
# or, ...
Design Pattern for Undo Engine
...e object is needed, you lookup the current definition of the object from a table. The table contains a linked list for each object that contains all the previous versions, along with information regarding which checkpoint they were active for.
Implementing undo/redo is simple: Do your action and es...
How to grant remote access permissions to mysql server for user?
...FIED BY 'YOUR_PASS'
WITH GRANT OPTION;
FLUSH PRIVILEGES;
*.* = DB.TABLE you can restrict user to specific database and specific table.
'root'@'%' you can change root with any user you created and % is to allow all IP. You can restrict it by changing %.168.1.1 etc too.
If that doesn't ...
Why use a READ UNCOMMITTED isolation level?
... sense for reading data will never be modified. Trying to use that to read tables that would be written to means that you will in practice read something that gets rolled back. It's not just that you are reading data that's a few seconds old, but you ....................................................
Working copy XXX locked and cleanup failed in SVN
...deleting a record in the SQLite ".svn\wc" file lock record in the WC_LOCK table.
I opened the "WC" file with SQLite editor and executed
delete from WC_LOCK
Following eakkas's comment, you might need to delete all the entries from WORK_QUEUE table as well.
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SQLite string contains other string query
...
Using LIKE:
SELECT *
FROM TABLE
WHERE column LIKE '%cats%' --case-insensitive
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SQL Server: Get data for only the past year
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This will have very bad performance on big tables, you query will loop over every record to evaluate the year value of the date, it would be better to use a date range
– Adriaan Davel
May 30 '12 at 15:43
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Tools for JPEG optimization? [closed]
... tools I could find, including MozJPEG and jpegoptim that optimize Huffman tables, progressive scans, and (optionally) remove invisible metadata.
If you don't have a Mac, I also have a basic web interface that works on any platform.
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How to get last N records with activerecord?
...rails is lazy, it will eventually hit the database with SQL like: "SELECT table.* FROM table ORDER BY table.id DESC LIMIT 5".
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How to delete from select in MySQL?
... clause.
Additionally, as shown in this answer you cannot modify the same table from a subquery within the same query. However, you can either SELECT then DELETE in separate queries, or nest another subquery and alias the inner subquery result (looks rather hacky, though):
DELETE FROM posts WHERE ...