大约有 15,640 项符合查询结果（耗时：0.0392秒） [XML]
Why does NULL = NULL evaluate to false in SQL server
...always evaluates to false. This is counterintuitive and has caused me many errors. I do understand the IS NULL and IS NOT NULL keywords are the correct way to do it. But why does SQL server behave this way?
...
Get free disk space
... RichardOD.
// Pinvoke for API function
[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool GetDiskFreeSpaceEx(string lpDirectoryName,
out ulong lpFreeBytesAvailable,
out ulong lpTotalNumberOfBytes,
out ulong lpT...
Run a PostgreSQL .sql file using command line arguments
...
Of course, you will get a fatal error for authenticating, because you do not include a user name...
Try this one, it is OK for me :)
psql -U username -d myDataBase -a -f myInsertFile
If the database is remote, use the same command with host
psql -h hos...
Razor HtmlHelper Extensions (or other namespaces for views) Not Found
...
I had this same error in an MVC 4 application using Razor. In an attempt to clean up the web.config files, I removed the two webpages: configuration values:
<appSettings>
<add key="webpages:Version" value="2.0.0.0" />
<ad...
Is JavaScript an untyped language?
...rect typing. Without implicit compiler interjection, the instruction will error during run-time.
"12345" * 1 === 12345 // string * number => number
Strongly typed means there is a compiler, and it wants you an explicit cast from string to integer.
(int) "12345" * 1 === 12345
In either cas...
How to reset postgres' primary key sequence when it falls out of sync?
...can occur due to unplanned database shutdowns, transaction rollbacks after errors, etc.
– Craig Ringer
Sep 20 '17 at 2:04
|
show 12 more com...
How do I change the number of open files limit in Linux? [closed]
When running my application I sometimes get an error about too many files open .
4 Answers
...
MySQL Cannot drop index needed in a foreign key constraint
...at new column. I'm trying to remove the current index but keep getting the error MySQL Cannot drop index needed in a foreign key constraint
...
How to get the first five character of a String
...g for length before hand.
The other way is to use String.Substring with error checking
like:
string firstFivCharWithSubString =
!String.IsNullOrWhiteSpace(yourStringVariable) && yourStringVariable.Length >= 5
? yourStringVariable.Substring(0, 5)
: yourStringVariable;
...
Cross field validation with Hibernate Validator (JSR 303)
...validations of the same type is via a list of annotations. This allows the error message to be specified per match.
For example, validating a common form:
@FieldMatch.List({
@FieldMatch(first = "password", second = "confirmPassword", message = "The password fields must match"),
@...