大约有 22,000 项符合查询结果（耗时：0.0765秒） [XML]
How do I check if a column is empty or null in MySQL?
...
This will select all rows where some_col is NULL or '' (empty string)
SELECT * FROM table WHERE some_col IS NULL OR some_col = '';
share
|
improve this answer
|
...
PostgreSQL query to return results as a comma separated list
...
SELECT string_agg(id::text, ',') FROM table
Requires PostgreSQL 9.0 but that's not a problem.
share
|
improve this answer
...
How to concatenate two strings to build a complete path
...ipt I want user to enter a path of a directory. Then I want to append some strings at the end of this string and build a path to some subdirectories.
For example assume user enters an string like this:
...
Check if a string contains a substring in SQL Server 2005, using a stored procedure
I've a string, @mainString = 'CATCH ME IF YOU CAN' . I want to check whether the word ME is inside @mainString .
2 Answ...
What is a plain English explanation of “Big O” notation?
...up them by matching color and pattern. We then exploit this to avoid doing extra work later (comparing puzzle pieces of like color to each other, not to every other single puzzle piece).
The moral of the story: a data structure lets us speed up operations. Even more, advanced data structures can l...
Static Vs. Dynamic Binding in Java
...le in Java
public class StaticBindingTest {
public static void main(String args[]) {
Collection c = new HashSet();
StaticBindingTest et = new StaticBindingTest();
et.sort(c);
}
//overloaded method takes Collection argument
public Collection sort(Collection ...
When should I use the HashSet type?
...
Here's a real example of where I use a HashSet<string>:
Part of my syntax highlighter for UnrealScript files is a new feature that highlights Doxygen-style comments. I need to be able to tell if a @ or \ command is valid to determine whether to show it in gray (valid)...
How do you sort a dictionary by value?
...
Use:
using System.Linq.Enumerable;
...
List<KeyValuePair<string, string>> myList = aDictionary.ToList();
myList.Sort(
delegate(KeyValuePair<string, string> pair1,
KeyValuePair<string, string> pair2)
{
return pair1.Value.CompareTo(pair2.Value);...
Meaning of “[: too many arguments” error from if [] (square brackets)
...
If your $VARIABLE is a string containing spaces or other special characters, and single square brackets are used (which is a shortcut for the test command), then the string may be split out into multiple words. Each of these is treated as a separat...
How to check for file lock? [duplicate]
...lar problem, I finished with the following code:
public bool IsFileLocked(string filePath)
{
try
{
using (File.Open(filePath, FileMode.Open)){}
}
catch (IOException e)
{
var errorCode = Marshal.GetHRForException(e) & ((1 << 16) - 1);
return err...