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What is the difference between join and merge in Pandas?
...e the main differences between df.join() and df.merge():
lookup on right table: df1.join(df2) always joins via the index of df2, but df1.merge(df2) can join to one or more columns of df2 (default) or to the index of df2 (with right_index=True).
lookup on left table: by default, df1.join(df2) uses...
How do you connect to multiple MySQL databases on a single webpage?
...ery database 1 pass the first link identifier:
mysql_query('select * from tablename', $dbh1);
and for database 2 pass the second:
mysql_query('select * from tablename', $dbh2);
If you do not pass a link identifier then the last connection created is used (in this case the one represented by $d...
PostgreSQL - fetch the row which has the Max value for a column
I'm dealing with a Postgres table (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id
...
Frequency table for a single variable
One last newbie pandas question for the day: How do I generate a table for a single Series?
4 Answers
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MySQL and GROUP_CONCAT() maximum length
...T SESSION group_concat_max_len = 1000000;
select group_concat(column) from table group by column
You can do this even in sharing hosting, but when you use an other session, you need to repeat the SET SESSION command.
share...
How may I align text to the left and text to the right in the same line?
...untime that it looks bad.
What I like to do is simply create a single row table and apply the right float on the second cell. No need to apply a left-align on the first, that happens by default. This handles overlap perfectly by word-wrapping.
HTML
<table style="width: 100%;">
<tr>&...
Get properties and values from unknown object
...
Here's something I use to transform an IEnumerable<T> into a DataTable that contains columns representing T's properties, with one row for each item in the IEnumerable:
public static DataTable ToDataTable<T>(IEnumerable<T> items)
{
var table = CreateDataTableForPropertiesO...
Why malloc+memset is slower than calloc?
...n parts here: your program, the standard library, the kernel, and the page tables. You already know your program, so...
Memory allocators like malloc() and calloc() are mostly there to take small allocations (anything from 1 byte to 100s of KB) and group them into larger pools of memory. For exam...
Secure hash and salt for PHP passwords
... etc, can actually reduce entropy by making the password scheme more predictable. I do agree. Randomess, as truly random as possible, is always the safest but least memorable solution.
So far as I've been able to tell, making the world's best password is a Catch-22. Either its not memorable, too pr...
How can I convert bigint (UNIX timestamp) to datetime in SQL Server?
...ved simply as: select dbo.fn_ConvertToDateTime( src_column/1000 ) from src_table;
– access_granted
Jan 10 '19 at 4:42
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