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What does .SD stand for in data.table in R
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.SD stands for something like "Subset of Data.table". There's no significance to the initial ".", except that it makes it even more unlikely that there will be a clash with a user-defined column name.
If this is your data.table:
DT = data.table(x=rep(c("a","b","c"),eac...
Get record counts for all tables in MySQL database
Is there a way to get the count of rows in all tables in a MySQL database without running a SELECT count() on each table?
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Which SQL query is faster? Filter on Join criteria or Where clause?
...LEFT JOIN.
In your very case this will look like this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAID = a.ID
AND a.ID = 1
LEFT JOIN
TableB b
ON x.TableBID = b.ID
or this:
SELECT *
FROM TableA a
LEFT JOIN
TableXRef x
ON x.TableAI...
How to use ng-repeat without an html element
... on tbody? (AFAIK, it is okay to have multiple <tbody>s in a single table.)
<tbody ng-repeat="row in array">
<tr ng-repeat="item in row">
<td>{{item}}</td>
</tr>
</tbody>
...
Specifying an Index (Non-Unique Key) Using JPA
...rsistence.Entity;
import javax.persistence.Index;
import javax.persistence.Table;
@Entity
@Table(name = "region",
indexes = {@Index(name = "my_index_name", columnList="iso_code", unique = true),
@Index(name = "my_index_name2", columnList="name", unique = false)})
publi...
Efficiently updating database using SQLAlchemy ORM
...ows one by one.
Instead you should do this:
session.execute(update(stuff_table, values={stuff_table.c.foo: stuff_table.c.foo + 1}))
session.commit()
This will execute as one query as you would expect, and because at least the default session configuration expires all data in the session on commi...
In jQuery, how do I get the value of a radio button when they all have the same name?
...dflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<table>
<tr>
<td>Sales Promotion</td>
<td><input type="radio" name="q12_3" value="1">1</td>
<td><input type="radio" name="q12_3" value="2">2</td>
...
Which method performs better: .Any() vs .Count() > 0?
...esh look on the problem.
Testing env:
EF 6.1.3, SQL Server, 300k records
Table model:
class TestTable
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Surname { get; set; }
}
Test code:
class Program
{
static void Main()
{
usi...
How to reset db in Django? I get a command 'reset' not found error
...I needed not just to flush the values in the database, but to recreate the tables properly. I'm not using migrations yet (early days) so I really needed to drop all the tables.
Two ways I've found to drop all tables, both require something other than core django.
If you're on Heroku, drop all t...
Using Auto Layout in UITableView for dynamic cell layouts & variable row heights
How do you use Auto Layout within UITableViewCell s in a table view to let each cell's content and subviews determine the row height (itself/automatically), while maintaining smooth scrolling performance?
...