大约有 41,000 项符合查询结果（耗时：0.0485秒） [XML]
Does Foreign Key improve query performance?
...the foreign key relationship already inforces that for you.
So this:
select p.ProductId, p.Name, c.CategoryId, c.Name AS Category
from Products p inner join ProductCategories c on p.CategoryId = c.CategoryIdwhere c.CategoryId = 1;
Becomes this:
SELECT p.ProductId, p.Name, c.CategoryId, c.N...
Access denied for user 'root@localhost' (using password:NO)
...etting of the root user ;
mysql> use mysql;
Database changed
mysql> select * from user;
Empty set (0.00 sec)
mysql> truncate table user;
Query OK, 0 rows affected (0.00 sec)
mysql> flush privileges;
Query OK, 0 rows affected (0.01 sec)
mysql> grant all privileges on *.* to root@loca...
How to debug stream().map(…) with lambda expressions?
... illustrate:
1- Press F7 (step into) key, will display the highlights (or selection mode)
2- Use Tab multiple times to select the snippet to debug
3- Press F7 (step into) key to step into
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Solving a “communications link failure” with JDBC and MySQL [duplicate]
... TOMCAT6_SECURITY=no
use validationQuery property
use validationQuery="select now()" to make sure each query has responses
AutoReconnect
Add this code to your connection string:
&autoReconnect=true&failOverReadOnly=false&maxReconnects=10
Although non of these solutions worke...
string.ToLower() and string.ToLowerInvariant()
... cultures. A Frenchman does not write SÉLECTIONNEZ x DE books instead of SELECT X FROM books. However, in order for the above code to work, a Turkish person would need to write SELECT x FROM books WHERE Author LİKE '%Adams%' (note the dot above the capital i, almost impossible to see). This wou...
How do I create a unique constraint that also allows nulls?
...dy found separately in other, properly defined columns. It should never be selected or used.
So, my story is that this is not a surrogate NULL, and I'm sticking to it! Since we don't actually want the non-NULL value for any purpose other than to trick the UNIQUE index to ignore NULLs, our use case ...
Eclipse interface icons very small on high resolution screen in Windows 8.1
... > compatibility > tick on 'Override high DPI scaling behaviour' and select System Enhanced from the dropdown as shown on pic below. Relaunch eclipse after changes.
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How to configure socket connect timeout
...ame problem by making the socket non-blocking and then putting the fd in a select/poll loop with a timeout value equal to the amount of time we are willing to wait for the connect to succeed.
I found this for Visual C++ and the explanation there also bends towards the select/poll mechanism I expla...
How to create a multiline UITextfield?
...tiline text.
In Interface Builder, add a UITextView where you want it and select the "editable" box. It will be multiline by default.
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How to create a date and time picker in Android? [closed]
.... This Date object contains
// the date and time that the user has selected.
}
@Override
public void onDateTimeCancel()
{
// Overriding onDateTimeCancel() is optional.
}
};
Then you create and show the dialog:
new SlideDateTimePicker.Builder(getSupportFragment...