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What makes a SQL statement sargable?
...non-sargable is to include a field inside a function in the where clause:
SELECT ... FROM ...
WHERE Year(myDate) = 2008
The SQL optimizer can't use an index on myDate, even if one exists. It will literally have to evaluate this function for every row of the table. Much better to use:
WHERE myDat...
Is it possible to use JS to open an HTML select to show its option list? [duplicate]
Is it possible to use JavaScript to open an HTML select to show its option list?
11 Answers
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How to delete or add column in SQLITE?
... as long as you do a create new table first instead of a create from select, it will have all those things.
– John Lord
Jul 3 '19 at 15:28
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select、poll、epoll之间的区别总结[整理] - C/C++ - 清泛网 - 专注C/C++及内核技术
select、poll、epoll之间的区别总结[整理]select，poll，epoll都是IO多路复用的机制。I O多路复用就通过一种机制，可以监视多个描述符，一旦某个描述符就绪（一般是读就绪或者写就绪...select，poll，epoll都是IO多路复用的机制。I/O多路...
SQL SERVER: Get total days between two dates
...:09.3312722';
DECLARE @enddate datetime2 = '2009-05-04 12:10:09.3312722';
SELECT DATEDIFF(day, @startdate, @enddate);
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Open directory dialog
I want the user to select a directory where a file that I will then generate will be saved. I know that in WPF I should use the OpenFileDialog from Win32, but unfortunately the dialog requires file(s) to be selected - it stays open if I simply click OK without choosing one. I could "hack up" the f...
How to fix “no valid 'aps-environment' entitlement string found for application” in Xcode 4.3?
...rrect in the build settings.
You need to make sure the correct profile is selected for the "Debug" configuration, and to be safe, that you have selected the correct profile for both the "Debug" and child-node labelled "Any iOS SDK":
Although this screenshot shows the "Automatic Developer" profil...
LINQ: Select an object and change some properties without creating a new object
.... But here is the expanded LINQ expression example.
var query = someList.Select(x => { x.SomeProp = "foo"; return x; })
What this does is use an anonymous method vs and expression. This allows you to use several statements in one lambda. So you can combine the two operations of setting the ...
Why do we always prefer using parameters in SQL statements?
I am very new to working with databases. Now I can write SELECT , UPDATE , DELETE , and INSERT commands. But I have seen many forums where we prefer to write:
...
Get table column names in MySQL?
...DESCRIBE my_table;
Or in newer versions you can use INFORMATION_SCHEMA:
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'my_database' AND TABLE_NAME = 'my_table';
Or you can use SHOW COLUMNS:
SHOW COLUMNS FROM my_table;
...