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When and why are database joins expensive?
...s back to mitigating the size of the working set. Joins involving properly selected keys with correctly set up indexes are cheap, not expensive, because they allow significant pruning of the result before the rows are materialised.
Materialising the result involves bulk disk reads which are the mo...
What is the C# version of VB.net's InputDialog?
...isualBasic:
In Solution Explorer right-click on the References folder.
Select Add Reference...
In the .NET tab (in newer Visual Studio verions - Assembly tab) - select Microsoft.VisualBasic
Click on OK
Then you can use the previously mentioned code:
string input = Microsoft.VisualBasic.Int...
How do I check/uncheck all checkboxes with a button using jQuery?
...ecking/unchecking the parent checkbox all the child checkboxes are getting selected/deselected also with the text of parent checkbox getting changed to checkall/uncheckall.
...
Group by with multiple columns using lambda
....Key.Country == "Ireland" && a.Key.Gender == "M")
.SelectMany(a => a)
.ToList();
Where CustomerGroupingKey takes the group keys:
private class CustomerGroupingKey
{
public CustomerGroupingKey(string country, string gender)
{
...
Android SDK on a 64-bit linux machine
...to current install instructions: developer.android.com/studio/install.html select 'linux' on the top right platform selection box.
– amotzg
Jul 6 '17 at 6:35
...
Generate C# class from XML
... file as classes.
Copy your XML file's content to clipboard
In editor, select place where you want your classes to be pasted
From the menu, select EDIT > Paste Special > Paste XML As Classes
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Could not load file or assembly Microsoft.SqlServer.management.sdk.sfc version 11.0.0.0
...ckoverflow.com/a/19246011/1030460 answer but focus on the error version to select the download instead of focusing on SQL Server version.
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What Java ORM do you prefer, and why? [closed]
...ay give jOOQ a try. You'll love it! :-)
Check out this example SQL:
// Select authors with books that are sold out
SELECT *
FROM T_AUTHOR a
WHERE EXISTS (SELECT 1
FROM T_BOOK
WHERE T_BOOK.STATUS = 'SOLD OUT'
AND T_BOOK.AUTHOR_ID ...
Eclipse “Server Locations” section disabled and need to change to use Tomcat installation
...
Here is how I did it:
Right click on my tomcat server in "Servers" view, select "Properties…"
In the "General" panel, click on the "Switch Location" button
The "Location: [workspace metadata]" bit should have been replaced by something else.
Open (or close and reopen) the Overview screen for the...
Query a parameter (postgresql.conf setting) like “max_connections”
... SHOW, such as minimum
and maximum values.
For your original request:
SELECT *
FROM pg_settings
WHERE name = 'max_connections';
Finally, there is current_setting(), which can be nested in DML statements:
SELECT current_setting('max_connections');
Related:
How to test my ad-hoc SQL wit...